Signal transforming method and device

ABSTRACT

Provided are a signal transforming method and a signal transforming device. For example, the signal transforming method includes determining a minimum-value matrix and a maximum-value matrix with respect to elements of a matrix used in frequency transformation, wherein the minimum-value matrix is configured of elements of minimum value and the maximum-value matrix is configured of elements of maximum value; determining a maximum threshold value of a result value of a function indicating at least one selected from transform distortion, normalization, and orthogonality of the matrix; determining a transform matrix configured of elements that are greater than the elements of the minimum-value matrix and less than the elements of the maximum-value matrix at respective positions of the matrix, and in which the result value of the function is less than the maximum threshold value; and transforming an input signal by using the determined transform matrix.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/898,276filed on Dec. 14, 2015, which is a U.S. national stage application under35 USC 371 of International Application No. PCT/KR2014/005274, filed onJun. 16, 2014, in the Korean Intellectual Property Office, which claimspriority from Chinese Application No. 201310238184.0, filed on Jun. 14,2013, in the Chinese Intellectual Property Office, the disclosures ofwhich are incorporated herein by reference in their entireties.

TECHNICAL FIELD

Various embodiments relate to a digital signal processing field, andmore particularly, to a method and device for improving digital signaltransformation.

BACKGROUND ART

A video and image coding technology as in a digital signal processingmode is used for wide utilization of digital video and image which aremultimedia information. Video coding for current block-based videocoding hybrid frame generally includes prediction coding, transformationand quantization, entropy coding, and loop filter. Among them, thetransformation is to remove correlation between prediction residuals andto concentrate energies of the residuals, which may facilitate thesubsequent entropy coding and may improve the efficiency of the videocoding as a whole.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

A method and device which are effective in determining a transformmatrix used to transform an input signal may be provided.

Technical Solution

According to a first aspect of the present disclosure, there is provideda signal transforming method including determining a minimum-valuematrix and a maximum-value matrix with respect to elements of a matrixused in frequency transformation, wherein the minimum-value matrix isconfigured of elements of minimum value and the maximum-value matrix isconfigured of elements of maximum value; determining a maximum thresholdvalue of a result value of a function indicating at least one selectedfrom transform distortion, normalization, and orthogonality of thematrix; determining a transform matrix configured of elements that aregreater than the elements of the minimum-value matrix and less than theelements of the maximum-value matrix at respective positions of thematrix, and in which the result value of the function is less than themaximum threshold value; and transforming an input signal by using thedetermined transform matrix.

The determining of the minimum-value matrix and the maximum-value matrixmay include determining, based on a size of the matrix, a DCT matrixthat is a matrix used in a DCT transform; and determining, by using thedetermined DCT matrix, the minimum-value matrix and the maximum-valuematrix which are configured of integer elements.

The determining, by using the determined DCT matrix, of theminimum-value matrix and the maximum-value matrix may includedetermining the minimum-value matrix as a matrix including elementvalues obtained by multiplying each of elements of the determined DCTmatrix by a predetermined factor, rounding multiplication results of themultiplying, and then subtracting a predetermined value from results ofthe rounding; and determining the maximum-value matrix as a matrixincluding element values obtained by multiplying each of the elements ofthe determined DCT matrix by the predetermined factor, rounding theresults of the multiplying, and then adding the predetermined value tothe results of the rounding.

The determining of the maximum threshold value may include determining areference matrix including the element values obtained by multiplyingeach of the elements of the determined DCT matrix by the predeterminedfactor, and rounding the results of the multiplying; determining areference matrix function value that is a result value of a functionindicating at least one selected from transform distortion,normalization, and orthogonality of the reference matrix; anddetermining the reference matrix function value as the maximum thresholdvalue.

The determining of the maximum threshold value may include determining areference matrix that is a matrix configured of integer elements, basedon a method defined in H.265; determining a reference matrix functionvalue that is a result value of a function indicating at least oneselected from transform distortion, normalization, and orthogonality ofthe reference matrix; and determining the reference matrix functionvalue as the maximum threshold value.

The determining of the maximum threshold value may include determiningthe maximum threshold value by multiplying a number of rows of thetransform matrix by a predetermined value.

The transforming of the input signal by using the determined transformmatrix may include determining an input matrix that is a matrix withrespect to the input signal; and performing an operation on thedetermined transform matrix and the input matrix, and thus determiningan output matrix that is a matrix with respect to an output signal.

The determining of the output matrix may include determining a matrixtransposed from the determined transform matrix, and performing anoperation on the matrix transposed from the determined transform matrixand the input matrix, and thus determining an output matrix that is amatrix with respect to the output signal.

According to a second aspect of the present disclosure, there isprovided a signal transforming device including a range determinerconfigured to determine a minimum-value matrix and a maximum-valuematrix with respect to elements of a matrix used in frequencytransformation, wherein the minimum-value matrix is configured ofelements of minimum value and the maximum-value matrix is configured ofelements of maximum value; a maximum threshold value determinerconfigured to determine a maximum threshold value of a result value of afunction indicating at least one selected from transform distortion,normalization, and orthogonality of the matrix; a transform matrixdeterminer configured to determine a transform matrix configured ofelements that are greater than the elements of the minimum-value matrixand less than the elements of the maximum-value matrix at respectivepositions of the matrix, and in which the result value of the functionis less than the maximum threshold value; and a transformer configuredto transform an input signal by using the determined transform matrix.

The range determiner may be further configured to determine, based on asize of the matrix, a DCT matrix that is a matrix used in a DCTtransform, and to determine, by using the determined DCT matrix, theminimum-value matrix and the maximum-value matrix which are configuredof integer elements.

The range determiner may be further configured to determine theminimum-value matrix as a matrix including element values obtained bymultiplying each of elements of the determined DCT matrix by apredetermined factor, rounding multiplication results of themultiplying, and then subtracting a predetermined value from results ofthe rounding, and to determine the maximum-value matrix as a matrixincluding element values obtained by multiplying each of the elements ofthe determined DCT matrix by the predetermined factor, rounding theresults of the multiplying, and then adding the predetermined value tothe results of the rounding.

The maximum threshold value determiner may be further configured todetermine a reference matrix including the element values obtained bymultiplying each of the elements of the determined DCT matrix by thepredetermined factor, and rounding the results of the multiplying, todetermine a reference matrix function value that is a result value of afunction indicating at least one selected from transform distortion,normalization, and orthogonality of the reference matrix, and todetermine the reference matrix function value as the maximum thresholdvalue.

The maximum threshold value determiner may be further configured todetermine a reference matrix that is a matrix configured of integerelements, based on a method defined in H.265, to determine a referencematrix function value that is a result value of a function indicating atleast one selected from transform distortion, normalization, andorthogonality of the reference matrix, and to determine the referencematrix function value as the maximum threshold value.

The maximum threshold value determiner may be further configured todetermine the maximum threshold value by multiplying a number of rows ofthe transform matrix by a predetermined value.

The transformer may be further configured to determine an input matrixthat is a matrix with respect to the input signal, and to perform anoperation on the determined transform matrix and the input matrix andthus to determine an output matrix that is a matrix with respect to theoutput signal.

The transformer may be further configured to determine a matrixtransposed from the determined transform matrix, and to perform anoperation on the matrix transposed from the determined transform matrixand the input matrix and thus to determine an output matrix that is amatrix with respect to the output signal.

According to a third aspect of the present disclosure, there is provideda computer-readable recording medium having recorded thereon a programwhich, when executed by a computer, performs the method of the firstaspect.

Advantageous Effects

Various embodiments of the present invention may provide a signaltransforming method that is effective for performance of signaltransformation, particularly for frequency transform.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a scheme in which signal transformationis performed by a device, according to various embodiments.

FIG. 2 illustrates a flowchart for describing a method of determining atransform matrix, and transforming an input signal by using thetransform matrix, according to various embodiments.

FIG. 3 illustrates a flowchart for describing a method of determining aminimum-value matrix and a maximum-value matrix by using a DCT matrix,according to various embodiments.

FIG. 4A illustrates a flowchart for describing a method of determining amaximum threshold value by using a reference matrix, according tovarious embodiments.

FIG. 4B illustrates a flowchart for describing a method of determining amaximum threshold value by using a scheme defined in H.265, according tovarious embodiments.

FIG. 5 illustrates a flowchart for describing a method of determining anoutput matrix that is a matrix with respect to an output signal,according to various embodiments.

FIGS. 6A-6N illustrates diagrams for describing a method of determininga matrix M that is a reference matrix and a matrix A that is a transformmatrix, according to various embodiments.

FIG. 7 illustrates a block diagram of the device 10, according tovarious embodiments.

FIG. 8 illustrates a block diagram of a video encoding apparatus basedon coding units of a tree structure, according to an embodiment.

FIG. 9 illustrates a block diagram of a video decoding apparatus basedon coding units of a tree structure, according to an embodiment.

FIG. 10 illustrates a diagram for describing a concept of coding unitsaccording to an embodiment of the present invention.

FIG. 11 illustrates a block diagram of an image encoder based on codingunits, according to an embodiment of the present invention.

FIG. 12 illustrates a block diagram of an image decoder based on codingunits, according to an embodiment of the present invention.

FIG. 13 illustrates a diagram illustrating deeper coding units accordingto depths, and partitions, according to an embodiment of the presentinvention.

FIG. 14 illustrates a diagram for describing a relationship between acoding unit and transformation units, according to an embodiment of thepresent invention.

FIG. 15 illustrates a plurality of pieces of encoding informationaccording to depths, according to an embodiment of the presentinvention.

FIG. 16 is a diagram of deeper coding units according to depths,according to an embodiment of the present invention.

FIGS. 17, 18, and 19 are diagrams for describing a relationship betweencoding units, prediction units, and transformation units, according toembodiments of the present invention.

FIG. 20 illustrates a diagram for describing a relationship between acoding unit, a prediction unit, and a transformation unit, according toencoding mode information of Table 1.

FIG. 21 illustrates a diagram of a physical structure of a disc in whicha program is stored, according to an embodiment.

FIG. 22 illustrates a diagram of a disc drive for recording and readinga program by using the disc.

FIG. 23 illustrates a diagram of an overall structure of a contentsupply system for providing a content distribution service.

FIGS. 24 and 25 illustrate external and internal structures of a mobilephone to which a video encoding method and a video decoding method areapplied, according to embodiments.

FIG. 26 illustrates a digital broadcasting system employing acommunication system, according to an embodiment of the presentinvention.

FIG. 27 is a diagram illustrating a network structure of a cloudcomputing system using a video encoding apparatus and a video decodingapparatus, according to an embodiment of the present invention.

MODE OF THE INVENTION

Hereinafter, throughout various embodiments of the present inventiondescribed in the specification, an ‘image’ may generally indicate notonly a still image but may also indicate a moving picture such as avideo.

Hereinafter, throughout various embodiments of the present inventiondescribed in the specification, a capital alphabet may mean a matrix.

Hereinafter, a transform matrix described in the specification may meana matrix used to perform frequency transform, and may mean a transformkernel matrix. For example, the transform matrix may be used to performa DCT transform.

Hereinafter, with reference to FIGS. 1 through 27, an image dataprocessing method and device according to various embodiments aredisclosed.

In addition, throughout the specification, a singular form may includeplural forms, unless there is a particular description contrary thereto.

Hereinafter, embodiments will be described in detail with reference toaccompanying drawings. Those components that are the same or are incorrespondence are rendered the same reference numeral regardless of thefigure number, and redundant explanations therefor are omitted.

In video image coding standards such as JPEG, MPEG-1/2/4, and H.261,floating-point discrete cosine transform (DCT) may be used. In practice,precision of floating-point arithmetic of different hardware productsmay be different. Therefore, a mismatch may occur between a coder and adecoder with complying with these standards. In view of the above,H.264/AVC, H.265, and video coding standards such as AVS1 and AVS2 maybe used in performing integer transformation. In H.264/AVC and AVS, allvalues in a transform kernel are integers, a proportion between thevalues may not be directly associated with a DCT matrix, and modules ofeach transform basis may not be identical. A scaling operation and ascaling matrix corresponding thereto may be introduced during atransformation process. A maximum size of a transform in H.264/AVC andAVS may be 8×8. The introduction of the scaling operation may decreasecomplexity in many calculations. The scaling operation may simplify acalculation of the transformation process as a whole. However, when thesize of the transform becomes very large, such as 32×32 and 64×64, ifthe scaling operation is used, the calculation may be complicated. Inrecent international H.245 and AVS2 standards, an integer DCT transformmay be used. A transform matrix A that is a matrix with respect to thetransformation may be obtained by multiplying a DCT matrix includingirrational elements by a predetermined factor, as shown in formula (1).In formula (1) and subsequent formulas, Factor may be the predeterminedfactor.

A=int{DCT×Factor}  formula (1)

In formula (1), DCT is an irrational DCT matrix whose expression may beas shown in formula (2). “int” is a rounding function. When Factor isthe same and the rounding functions are different, obtained transformmatrices A may be different. Different predetermined factors androunding functions may obtain transform matrices having differenttransformation performances. The transformation performance may includetransform distortion, a decorrelation capability influenced byorthogonality and normalization of the transform basis. The design ofthe rounding function may have a significant impact on the wholetransformation.

$\begin{matrix}{{{DCT}\left( {i,j} \right)} = \left\{ \begin{matrix}{\frac{1}{\sqrt{N}},} & {i = 0} \\{{\sqrt{\frac{2}{N}} \times {\cos \left( \frac{\left( {{2 \times j} + 1} \right) \times i \times \pi}{2N} \right)}},} & {i \neq 0}\end{matrix} \right.} & {{formula}\mspace{14mu} (2)}\end{matrix}$

In formula (2), the size of the transform matrix is N×N.

The performance of each transform matrix in conventional H.265 may beimproved. Also, the performance related to the orthogonality and thenormalization of the transform basis may be improved. In AVS2 that isbeing developed, the decorrelation capability of a transform kernel maybe improved and the transform distortion resulting from the transformkernel may be decreased.

When the transform matrix is determined, the design of thetransformation process may have a significant impact on the performance.In the current AVS2 draft, the bit-width of data during thetransformation process may exceed 32-bit, and thus the design of thebit-width may be improved.

Therefore, the design of the transformation process may be improved inH.265 or AVS2 which is being developed. The transform matrix and thetransformation process may also be improved. In the video image coding,the decorrelation capability, the orthogonality, and the normalizationof an existing digital signal transform kernel may not be sufficient,which may result in excessive transform distortion and unsatisfactorytransformation performance.

FIG. 1 illustrates a diagram of a scheme in which signal transformationis performed by a device, according to various embodiments.

A device 10 may receive an input signal 12. The device 10 may processthe received input signal 12.

The device 10 may be used in encoding or may be used in decoding.

A method of improving performance of digital signal transformationaccording to various embodiments is described below. According to thesignal transforming method, a matrix A that is a N×N transform matrixmay be determined. The transform matrix A may satisfy conditions offormula (3) and formula (4).

[DCT(i,j)×Factor]−2≤A(i,j)≤[DCT(i,j)×Factor]+2  [formula (3)]

J(A)<TH  [formula (4)]

In formula (3), A(i,j) may represent an element in the i-th row and j-thcolumn of the transform matrix A. DCT(i,j) may represent an element inthe i-th row and j-th column of a DCT matrix. A definition of DCT(i,j)may be referred to the aforementioned formula (2). A predeterminedfactor may be a value that is greater than 1. [ ] may indicate rounding.

In formula (4), TH may represent a maximum threshold value. J(A) may bea function indicating at least one selected from transform distortion,normalization, and orthogonality of the matrix A as defined in formula(5). For example, J(A) may indicate a new transform rate-distortion costfunction defined in formula (5).

$\begin{matrix}{{J(A)} = \frac{{\alpha \times {{dist}(A)}} + {\beta \times {{norm}(A)}} + {\gamma \times {{orth}(A)}}}{\alpha + \beta + \gamma}} & \left\lbrack {{formula}\mspace{14mu} (5)} \right\rbrack\end{matrix}$

In formula (5), α, β, γ may represent three parameters that satisfy β<α,γ<α. Formula (5) may include three newly-defined factors associated withthe transformation performance. dist(A) may indicate a value associatedwith DCT distortion, normal(A) may indicate a value associated with thenormalization, and orth(A) may indicate a value associated with theorthogonality. For example, J(A) may represent a value indicating thedistortion, the normalization, and the orthogonality of the DCTtransform with respect to the transform matrix A.

For example, dist(A), normal(A), and orth(A) may be defined in formula(6).

$\begin{matrix}\left\{ \begin{matrix}{{{dist}(A)} = {\sum\limits_{i = 1}^{N}{\sum\limits_{{j = 1},{i \neq j}}^{N}\frac{{P\left( {i,j} \right)}}{{P\left( {i,i} \right)}}}}} \\{{{normal}\mspace{11mu} (A)} = {\sum\limits_{i = 1}^{N}{{{Q\left( {i,i} \right)} - 1}}}} \\{{{orth}(A)} = {\sum\limits_{i = 1}^{N}{\sum\limits_{{j = 1},{j \neq i}}^{N}{{Q\left( {i,j} \right)}}}}} \\{P = {A \times {DCT}^{T}}} \\{Q = \frac{A^{T} \times A}{{Factor}^{2}}}\end{matrix} \right. & \left\lbrack {{formula}\mspace{14mu} (6)} \right\rbrack\end{matrix}$

In the aforementioned formulas, “A” may represent an N×N transformmatrix. DCT may represent a DCT matrix including irrational elements. Asuperscript “T” may represent transpose of a matrix. α, β, γ mayrepresent three parameters that satisfy β<α, γ<α and are configuredaccording to actual situations. Here, a condition of α, β, γ thatsatisfy β<α, γ<α is an example, and another condition may be set.

Three examples of determining a value of TH are described.

In the first example of determining the maximum threshold value, it maybe determined as TH=J(M). M may be a matrix obtained by rounding eachelement in a calculation result obtained by multiplying the irrationalDCT matrix by the predetermined factor. For example, [DCT(i,j)×Factor]may be an element of M.

$\begin{matrix}{{J(M)} = \frac{{\alpha \times {{dist}(M)}} + {\beta \times {{norm}(M)}} + {\gamma \times {{orth}(M)}}}{\alpha + \beta + \gamma}} & \left\lbrack {{formula}\mspace{14mu} (7)} \right\rbrack\end{matrix}$

In formula (7), α, β, γ may satisfy a predetermined condition. Forexample, α, β, γ may satisfy β<α, γ<α.

An example of definitions of dist(M), normal(M), and orth(M) may beshown in formula (8).

$\begin{matrix}\left\{ \begin{matrix}{{{dist}(M)} = {\sum\limits_{i = 1}^{N}{\sum\limits_{{j = 1},{i \neq j}}^{N}\frac{{P\left( {i,j} \right)}}{{P\left( {i,i} \right)}}}}} \\{{{normal}\mspace{11mu} (M)} = {\sum\limits_{i = 1}^{N}{{{Q\left( {i,i} \right)} - 1}}}} \\{{{orth}(M)} = {\sum\limits_{i = 1}^{N}{\sum\limits_{{j = 1},{j \neq i}}^{N}{{Q\left( {i,j} \right)}}}}} \\{P = {M \times {DCT}^{T}}} \\{Q = \frac{M^{T} \times M}{{Factor}^{2}}}\end{matrix} \right. & \left\lbrack {{formula}\mspace{14mu} (8)} \right\rbrack\end{matrix}$

In the aforementioned formulas, “T” may represent transpose of a matrix.P(i,j) may represent an element in the i-th row and j-th column ofMatrix P. Q(i,j) may represent an element in the i-th row and j-thcolumn of Matrix Q. DCT may represent the DCT matrix includingirrational elements.

In the second example of determining the maximum threshold value, whenpredetermined factor=2̂6×N̂(½), N=4, 8, 16 or 32, and M is a transformmatrix defined in the H.265 standard, TH=J(M). However, this example isonly an embodiment, and according to the example, in order to obtain themaximum threshold value, the device 10 may determine a reference matrixor a transform matrix according to the H.264 or H.265 standard, mayapply the aforementioned formula (5) to the determined reference matrixor transform matrix, and thus may determine the maximum threshold value.

In the third example of determining the maximum threshold value, it maybe determined as TH=N×0.02.

A device for improving performance of the digital signal transformationaccording to various embodiments is described. According to the signaltransforming device, a matrix A that is an N×N transform matrix may bedetermined. The transform matrix A may satisfy conditions of theaforementioned formulas (3) and (4).

In formula (3), A(i,j) may represent an element in the i-th row and j-thcolumn of the matrix A. DCT(i,j) may represent an element in the i-throw and j-th column of a DCT matrix. The definition of DCT(i,j) may bereferred to formula (2) described below. A predetermined factor may begreater than 1. [ ] may indicate rounding.

In formula (4), TH may represent a maximum threshold value. For example,J(A) may indicate a new transform rate-distortion cost function definedin the formula (5).

In formula (5), α, β, γ may satisfy a predetermined condition. Forexample, α, β, γ may satisfy β<α, γ<α. Also, an example of definitionsof dist(A), normal(A), and orth(A) may be shown in formula (6).

In the aforementioned formulas, “T” may represent transpose of a matrix.P(i,j) may represent an element in the i-th row and j-th column ofMatrix P. Q(i,j) may represent an element in the i-th row and j-thcolumn of Matrix Q. DCT may represent a DCT matrix including irrationalelements.

According to the embodiment, the maximum threshold value determined bythe device may be J(M). M may be an N×N matrix obtained by rounding eachelement in a calculation result obtained by multiplying the DCT matrixincluding irrational elements by the predetermined factor. For example,[DCT(i,j)×Factor] may be an element of M.

In the aforementioned formula (7), α, β, γ may represent threeparameters that satisfy β<α, γ<α. Here, a condition of α, β, γ thatsatisfy β<α, γ<α is an example, and another condition may be set.

An example of definitions of dist(M), normal(M), and orth(M) may beshown in the aforementioned formula (8).

In the aforementioned formulas, “T” may represent transpose of a matrix.P(i,j) may represent an element in the i-th row and j-th column ofMatrix P. Q(i,j) may represent an element in the i-th row and j-thcolumn of Matrix Q. DCT may represent the irrational DCT matrix.

In another embodiment in which the device obtains the maximum thresholdvalue, when predetermined factor=2̂6×N̂(½), N=4, 8, 16 or 32, and M is atransform matrix defined in the H.265 standard, TH=J(M). The calculationof J(M) is the same as that of J(A) described above.

In another embodiment of obtaining the maximum threshold value,TH=N×0.02.

Various embodiments also describe a digital signal transforming methodusing the transform matrix determined by the method described in theaforementioned embodiments. The digital signal transforming method mayinclude methods described below.

One-dimensional transformation may be performed on atransformation-target data block X with an L×K matrix according to oneof the methods described below.

A matrix Y may be determined by multiplying a matrix A by a matrix X.For example, Y=A×X may be set. Also, a result obtained by adding w1 toeach element in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s1-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Lhave a same value, w1 and s1 are integers, and w1≥0, s1≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

A matrix Y may be determined by multiplying a matrix X by atransposed-matrix A. For example, Y=X×ÂT may be set. Also, a resultobtained by adding w2 to each element in the matrix Y may be expressedin the form of a natural binary, and the device 10 may obtain a resultof transformation by right shifting the result expressed in the form ofa natural binary by s2-bit. Here, A may be an N×N transform matrixdetermined by the aforementioned methods. Also, in the presentembodiment, a condition in which N and K have a same value, w2 and s2are integers, and w2≥0, s2≥0 may be satisfied. Here, the condition maybe an example, and another condition may be set.

A matrix Y may be determined by multiplying a matrix X by a matrix A.For example, Y=X×A may be set. Also, a result obtained by adding w3 toeach element in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s3-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Khave a same value, w3 and s3 are integers, and w3≥0, s3≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

A matrix Y may be determined by multiplying a transposed-matrix A by amatrix X. For example, Y=ÂT×X may be set. Also, a result obtained byadding w4 to each element in the matrix Y may be expressed in the formof a natural binary, and the device 10 may obtain a result oftransformation by right shifting the result expressed in the form of anatural binary by s4-bit. Here, A may be an N×N transform matrixdetermined by the aforementioned methods. Also, in the presentembodiment, a condition in which N and L have a same value, w4 and s4are integers, and w4≥0, s4≥0 may be satisfied. Here, the condition maybe an example, and another condition may be set.

Various embodiments also include a digital signal transforming device.The digital signal transforming device may perform one-dimensionaltransformation on a transformation-target data block X with an L×Kmatrix, according to one of the methods described below.

A matrix Y may be determined by multiplying a matrix A by a matrix X.For example, Y=A×X may be set. Also, a result obtained by adding w1 toeach element in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s1-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Lhave a same value, w1 and s1 are integers, and w1≥0, s1≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

A matrix Y may be determined by multiplying a matrix X by atransposed-matrix A. For example, Y=X×ÂT may be set. Also, a resultobtained by adding w2 to each element in the matrix Y may be expressedin the form of a natural binary, and the device 10 may obtain a resultof transformation by right shifting the result expressed in the form ofa natural binary by s2-bit. Here, A may be an N×N transform matrixdetermined by the aforementioned methods. Also, in the presentembodiment, a condition in which N and K have a same value, w2 and s2are integers, and w2≥0, s2≥0 may be satisfied. Here, the condition maybe an example, and another condition may be set.

A matrix Y may be determined by multiplying a matrix X by a matrix A.For example, Y=X×A may be set. Also, a result obtained by adding w3 toeach element in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s3-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Khave a same value, w3 and s3 are integers, and w3≥0, s3≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

A matrix Y may be determined by multiplying a transposed-matrix A by amatrix X. For example, Y=ÂT×X may be set. Also, a result obtained byadding w4 to each element in the matrix Y may be expressed in the formof a natural binary, and the device 10 may obtain a result oftransformation by right shifting the result expressed in the form of anatural binary by s4-bit. Here, A may be an N×N transform matrixdetermined by the aforementioned methods. Also, in the presentembodiment, a condition in which N and L have a same value, w4 and s4are integers, and w4≥0, s4≥0 may be satisfied. Here, the condition maybe an example, and another condition may be set.

FIG. 2 illustrates a flowchart for describing a method of determining atransform matrix, and transforming an input signal by using thetransform matrix, according to various embodiments.

In operation S210, the device 10 may determine a minimum-value matrixand a maximum-value matrix with respect to elements of a matrix used infrequency transformation, wherein the minimum-value matrix is configuredof the elements of minimum value and the maximum-value matrix isconfigured of the elements of maximum value.

“[DCT(i,j)×Factor]−2” described in the aforementioned formula (3) may bean element of the minimum-value matrix.

Also, “[DCT(i,j)×Factor]+2” described in the aforementioned formula (3)may be an element of the maximum-value matrix.

Therefore, the device 10 may determine a minimum-value matrix and amaximum-value matrix with respect to a transform matrix used in a DCTtransform.

In operation S220, the device 10 may determine a maximum threshold valueof a result value of a function indicating at least one selected fromtransform distortion, normalization, and orthogonality of the matrix.

In an example of determining the result value of the function, a resultvalue of a function indicating at least one selected from transformdistortion, normalization, and orthogonality of a transform matrix A,may be determined by applying the transform matrix A to formula (5).Here, a value of J(A) may be the result value of the function.

In an example of determining the maximum threshold value, when“[DCT(i,j)×Factor]” described in the aforementioned formula (3) is avalue of M(i,j), a value of J(M) obtained according to formula (7) maybe the maximum threshold value of the transform matrix A.

Also, in an embodiment, when the maximum threshold value is TH, thetransform matrix A may satisfy the aforementioned formula (4). In orderto determine J(A), formula (5) and formula (6) may be used.

In operation S230, the device 10 may determine a transform matrixconfigured of elements that are greater than the elements of theminimum-value matrix and are less than the elements of the maximum-valuematrix at respective positions of the matrix, and in which the resultvalue of the function is less than the maximum threshold value.

For example, the transform matrix A may satisfy the aforementionedformulas (3) and (4). An example of the transform matrix A thatsatisfies the aforementioned formulas (3) and (4) is described at alater time with reference to FIG. 6.

In operation S240, the device 10 may transform an input signal by usingthe determined transform matrix.

For example, by multiplying a matrix corresponding to the input signalby the transform matrix A, a matrix corresponding to an output signalmay be obtained.

As another example, by multiplying the transform matrix A by the matrixcorresponding to the input signal, a matrix corresponding to an outputsignal may be obtained.

As another example, by multiplying the matrix corresponding to the inputsignal by a transposed-transform matrix A, a matrix corresponding to anoutput signal may be obtained.

As another example, by multiplying the transposed-transform matrix A bythe matrix corresponding to the input signal, a matrix corresponding toan output signal may be obtained.

FIG. 3 illustrates a flowchart for describing a method of determining aminimum-value matrix and a maximum-value matrix by using a DCT matrix,according to various embodiments.

In operation S310, the device 10 may determine, based on a size of amatrix, the DCT matrix that is a matrix used in a DCT transform. The DCTmatrix may include elements of irrational value.

The DCT matrix may be the matrix used when the DCT transform isperformed. Also, the DCT matrix may include the irrational elements.Also, as described above, the DCT matrix may be determined by usingformula (2).

In addition, the device 10 may use a size of a transform matrix so as todetermine the DCT matrix. For example, when a value of N in formula (2)which is the size of the transform matrix is determined, the device 10may determine values of the elements of the DCT matrix.

In operation S320, the device 10 may determine a minimum-value matrix asa matrix including element values obtained by multiplying each of theelements of the DCT matrix by a predetermined factor, rounding resultsof the multiplying, and then subtracting a predetermined value fromresults of the rounding, wherein the elements of the DCT matrix aredetermined in operation S310.

For example, “[DCT(i,j)×Factor]−2” described in formula (3) may be anelement of the minimum-value matrix. For example, the device 10 maydetermine the minimum-value matrix as a matrix including element valuesobtained by multiplying each of the elements of the DCT matrix by apredetermined factor, rounding multiplication results, and thensubtracting 2 from the results of the rounding.

As another example, the device 10 may determine the minimum-value matrixas a matrix including elements obtained through “[DCT(i,j)×3]−7”.

In operation S330, the device 10 may determine a maximum-value matrix asa matrix including element values obtained by multiplying each of theelements of the DCT matrix by a predetermined factor, rounding theresults of the multiplying, and then adding a predetermined value to theresults of the rounding, wherein the elements of the DCT matrix aredetermined in operation S310.

As another example, the device 10 may determine the maximum-value matrixas a matrix including elements obtained through “[DCT(i,j)×3]+7”.

FIG. 4A illustrates a flowchart for describing a method of determining amaximum threshold value by using a reference matrix, according tovarious embodiments.

In operation S410, the device 10 may determine a reference matrixincluding element values obtained by multiplying each of elements of adetermined DCT matrix by a predetermined factor, and rounding results ofthe multiplying.

For example, the reference matrix may indicate a matrix obtained bymultiplying the DCT matrix including irrational elements by thepredetermined factor and rounding each of the elements in calculationresults. For example, the reference matrix may indicate the matrix M.For example, [DCT(i,j)×Factor] may be an element of the matrix M.

In operation S420, the device 10 may determine a reference matrixfunction value that is a result value of a function indicating at leastone selected from transform distortion, normalization, and orthogonalityof the reference matrix.

For example, J(M) in the aforementioned formula (7) may represent thereference matrix function value.

Also, the reference matrix function value may be a rate-distortion cost.For example, J(M) in the aforementioned formula (7) may represent arate-distortion cost of the reference matrix.

As another example, a rate-distortion cost of the reference matrix whichis obtained by using a general rate-distortion cost calculating methodmay be the reference matrix function value.

In operation S430, the device 10 may determine, as the maximum thresholdvalue, the reference matrix function value which is determined inoperation S420.

For example, the device 10 may determine, as the maximum thresholdvalue, a value of J(M) in the aforementioned formula (7).

As another example, the device 10 may determine, as the maximumthreshold value, a value of the rate-distortion cost obtained by usingthe general rate-distortion cost calculating method.

Although not illustrated in FIG. 4, the maximum threshold value may bepreset as a predetermined value. For example, the maximum thresholdvalue may be preset as 0.2. As another example, the maximum thresholdvalue may be preset as a predetermined value that is determined by usinga preset variable. For example, when a matrix used in frequencytransform is N×N, the maximum threshold value may be N×0.02.

FIG. 4B illustrates a flowchart for describing a method of determining amaximum threshold value by using a method defined in H.265, according tovarious embodiments.

In operation S440, the device 10 may determine a reference matrix thatis a matrix configured of integer elements, based on the method definedin H.265.

For example, a reference matrix determining method may be defined inH.265, and the device 10 may determine the reference matrix, accordingto the reference matrix determining method defined in H.265. Inaddition, an element of the reference matrix may be an integer.

Operations S450 and S460 correspond to operations S420 and S430,respectively, thus, detailed descriptions thereof are omitted here tomake an overall description simple.

FIG. 5 illustrates a flowchart for describing a method of determining anoutput matrix that is a matrix with respect to an output signal,according to various embodiments.

In operation S510, the device 10 may determine an input matrix that is amatrix with respect to an input signal.

For example, the device 10 may express the input signal in a matrixform, and the matrix expressed in a matrix form, from the input signal,by the device 10, may be the input matrix.

In operation S520, the device 10 may determine a matrix transposed froma transform matrix determined by using a predetermined method.

The transpose may indicate a type of an operation of switching a row anda column. If it is assumed that a transform matrix is a matrix A, thetransposed matrix A may be expressed as ÂT.

In operation S530, the device 10 may perform an operation on thetransposed matrix, which is determined in operation S520, and the inputmatrix, and thus may determine the output matrix that is the matrix withrespect to the output signal.

For example, it may be assumed that the transform matrix is the matrixA, the input matrix is a matrix X, and the output matrix is a matrix Y.

In an example of determining the output matrix, the matrix Y may bedetermined by multiplying the matrix A by the matrix X. For example,Y=A×X may be set. Also, a result obtained by adding w1 to each elementin the matrix Y may be expressed in the form of a natural binary, andthe device 10 may obtain a result of transformation by right shiftingthe result expressed in the form of a natural binary by s1-bit. Here, Amay be an N×N transform matrix determined by the aforementioned methods.Also, in the present embodiment, a condition in which N and L have asame value, w1 and s1 are integers, and w1≥0, s1≥0 may be satisfied.Here, the condition may be an example, and another condition may be set.

In another example of determining the output matrix, the matrix Y may bedetermined by multiplying the matrix X by a transposed-matrix A. Forexample, Y=X×ÂT may be set. Also, a result obtained by adding w2 to eachelement in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s2-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Khave a same value, w2 and s2 are integers, and w2≥0, s2≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

In another example of determining the output matrix, the matrix Y may bedetermined by multiplying a matrix X by a matrix A. For example, Y=X×Amay be set. Also, a result obtained by adding w3 to each element in thematrix Y may be expressed in the form of a natural binary, and thedevice 10 may obtain a result of transformation by right shifting theresult expressed in the form of a natural binary by s3-bit. Here, A maybe an N×N transform matrix determined by the aforementioned methods.Also, in the present embodiment, a condition in which N and K have asame value, w3 and s3 are integers, and w3≥0, s3≥0 may be satisfied.Here, the condition may be an example, and another condition may be set.

In another example of determining the output matrix, the matrix Y may bedetermined by multiplying a transposed-matrix A by a matrix X. Forexample, Y=ÂT×X may be set. Also, a result obtained by adding w4 to eachelement in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s4-bit.Here, A may be an N×N transform matrix determined by the aforementionedmethods. Also, in the present embodiment, a condition in which N and Lhave a same value, w4 and s4 are integers, and w4≥0, s4≥0 may besatisfied. Here, the condition may be an example, and another conditionmay be set.

With reference to FIGS. 6A through 6N, various embodiments are describedin detail.

FIG. 6 illustrates diagrams for describing a method of determining amatrix M that is a reference matrix and a matrix A that is a transformmatrix, according to various embodiments.

FIGS. 6A and 6B illustrate diagrams for describing a method ofdetermining a matrix M that is a reference matrix and a matrix A that isa transform matrix, according to various embodiments.

FIGS. 6A and 6B illustrate a first embodiment.

While an actual 8×8 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 9 bits. For example, formula (9) may besatisfied.

Factor=256√{square root over (2)}  [formula (9)]

For example, α=3, β=γ=0. Also, the transform matrix A may satisfy theaforementioned formulas (3) and (4).

TH that is a maximum threshold value may be obtained by using a methodbelow.

When a condition of formula (9) is satisfied, the matrix M may beobtained by performing rounding according to formula (1), and FIG. 6Aillustrates an example of the matrix X.

When the matrix M is as shown in FIG. 6A, J(M)=0.015159 may be confirmedvia calculation. TH that is the maximum threshold value may be set asJ(M).

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.015159} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Billustrates an example of the transform matrix A.

When the matrix A is as shown in FIG. 6B, J(A)=0.014621 may be confirmedvia calculation.

FIGS. 6C and 6D illustrate diagrams for describing a method ofdetermining a matrix M that is a reference matrix and a matrix A that isa transform matrix, according to various embodiments.

FIGS. 6C and 6D illustrate a second embodiment.

While an actual 16×16 transformation process is performed,implementation of the transformation may satisfy requirements. Each ofcoefficients in the transform matrix A may be an integer and a storagespace of each coefficient may not exceed 8 bits. For example, formula(10) may be satisfied.

Factor=256  [formula (10)]

For example, α=2, β=γ=1. Also, the transform matrix A may satisfy theaforementioned formulas (3) and (4).

TH that is a maximum threshold value may be obtained by using a methodbelow.

A matrix M may be a 16×16 transform matrix defined in the H.265standard, and FIG. 6A illustrates an example of the matrix M.

When the matrix M is as shown in FIG. 6C, J(M)=0.13377 may be confirmedvia calculation. TH that is the maximum threshold value may be set asJ(M).

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.13377} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Dillustrates an example of the transform matrix A.

When the matrix A is as shown in FIG. 6D, J(A)=0.080737 may be confirmedvia calculation.

FIGS. 6E and 6F illustrate diagrams for describing a method ofdetermining a matrix M that is a reference matrix and a matrix A that isa transform matrix, according to various embodiments.

FIGS. 6E and 6F illustrate a third embodiment.

While an actual 8×8 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 8 bits. For example, formula (11) may besatisfied.

Factor=128√{square root over (2)}  [formula (11)]

For example, α=2, β=γ=1. Also, the transform matrix A may satisfy theaforementioned formulas (3) and (4).

TH that is a maximum threshold value may be obtained by using a methodbelow.

The matrix M may be an 8×8 transform matrix defined in the H.265standard, and FIG. 9A illustrates an example of the matrix M.

When the matrix M is as shown in FIG. 6E, J(M)=0.038484 may be confirmedvia calculation. TH that is the maximum threshold value may be set asJ(M).

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.038484} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Fillustrates an example of the transform matrix A.

When the matrix A is as shown in FIG. 6F, J(A)=0.02687 may be confirmedvia calculation.

FIGS. 6G and 6H illustrate diagrams for describing a method ofdetermining a matrix M that is a reference matrix and a matrix A that isa transform matrix, according to various embodiments.

FIGS. 6G and 6H illustrate a fourth embodiment.

While an actual 4×4 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 8 bits. For example, formula (12) may besatisfied.

Factor=128  [formula (12)]

For example, α=4, β=γ=1. Also, the transform matrix A may satisfy theaforementioned formulas (3) and (4).

TH that is a maximum threshold value may be obtained by using a methodbelow.

The matrix M may be a 4×4 transform matrix defined in the H.265standard, and FIG. 10A illustrates an example of the matrix M.

When the matrix M is as shown in FIG. 6G, J(M)=0.022349 may be confirmedvia calculation. TH that is the maximum threshold value may be set asJ(M).

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.022349} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Hillustrates an example of the transform matrix A.

When the matrix A is as shown in FIG. 6H, J(A)=0.006411 may be confirmedvia calculation.

FIGS. 6I and 6J illustrate diagrams for describing a method ofdetermining a matrix M that is a reference matrix and a matrix A that isa transform matrix, according to various embodiments.

FIGS. 6I and 6J illustrate a fifth embodiment.

While an actual 8×8 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 7 bits. For example, formula (13) may besatisfied.

Factor=64√{square root over (2)}  [formula (13)]

For example, α=5, β=1.5, γ=1. Also, the transform matrix A may satisfythe aforementioned formulas (3) and (4).

TH that is a maximum threshold value may be obtained by using a methodbelow.

The matrix M may be an 8×8 transform matrix defined in RD 3.0 that isreference software of AVS2, and FIG. 6I illustrates an example of thematrix M.

When the matrix M is as shown in FIG. 6I, J(M)=0.068060 may be confirmedvia calculation. TH that is the maximum threshold value may be set asJ(M).

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.068060} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Jillustrates an example of the transform matrix A.

When the matrix A is as shown in FIG. 6J, J(A)=0.055759 may be confirmedvia calculation.

FIG. 6K illustrates a diagram for describing a method of determining amatrix A that is a transform matrix, according to various embodiments.

FIG. 6K illustrates a sixth embodiment.

While an actual 32×32 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 7 bits. For example, formula (11) may besatisfied. For example, Factor=128√{square root over (2)}.

For example, α=2, β=1.5, γ=1. Also, the transform matrix A may satisfythe aforementioned formulas (3) and (4).

TH that is a maximum threshold value may be 32×0.02=0.64.

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.64} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Killustrates an example of the 32×32 transform matrix A, whenJ(A)=0.437463.

FIG. 6L illustrates a diagram for describing a method of determining amatrix A that is a transform matrix, according to various embodiments.

FIG. 6L illustrates a seventh embodiment.

While an actual 32×32 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 8 bits. For example, formula (9) may besatisfied. For example, Factor=256√{square root over (2)}.

For example, α=6, β=1, γ=1.5. Also, the transform matrix A may satisfythe aforementioned formula (3) and J(A)<TH.

TH that is a maximum threshold value may be 32×0.02=0.64.

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.64} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Lillustrates an example of the 32×32 transform matrix A, whenJ(A)=0.271159.

FIG. 6M illustrates a diagram for describing a method of determining amatrix A that is a transform matrix, according to various embodiments.

FIG. 6M illustrates an eighth embodiment.

While an actual 16×16 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 7 bits. For example, formula (12) may besatisfied. For example, a predetermined factor=128.

For example, α=3, β=1, γ=1. Also, the transform matrix A may satisfy theaforementioned formula (3) and J(A)<TH.

TH that is a maximum threshold value may be 16×0.02=0.32.

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.32} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Millustrates an example of the 16×16 transform matrix A, whenJ(A)=0.158616.

FIG. 6N illustrates a diagram for describing a method of determining amatrix A that is a transform matrix, according to various embodiments.

FIG. 6N illustrates a ninth embodiment.

While an actual 4×4 transform process is performed, implementation ofthe transform may satisfy requirements. Each of coefficients in thetransform matrix A may be an integer and a storage space of eachcoefficient may not exceed 7 bits. For example, a predeterminedfactor=64.

For example, α=3, β=1, γ=1. Also, the transform matrix A may satisfy theaforementioned formula (3) and J(A)<TH.

TH that is a maximum threshold value may be 4×0.02=0.08.

The transform matrix A may be written as a member of a set. For example,A may satisfy A∈{S:J(S)<0.08} and the aforementioned formula (3). Afinite number of the transform matrix may be limitedly obtained. FIG. 6Nillustrates an example of the 4×4 transform matrix A, when J(A)=0.01069.

A tenth embodiment is described below.

During an actual transform process, a size of a transformation targetdata block X may be 16×16 and a data bit-width of the data block X maybe n-bit. A transform matrix A may be a 16×16 matrix that satisfies acondition of J(A)<TH described in the second embodiment. In this case,it may be required that a data bit-width of a transformed data block Ydoes not exceed r-bit. The transform process is described below.

A matrix Y may be determined by multiplying a matrix A by a matrix X.For example, Y=A×X may be set. Also, a result obtained by adding w toeach element in the matrix Y may be expressed in the form of a naturalbinary, and the device 10 may obtain a result of transformation by rightshifting the result expressed in the form of a natural binary by s-bit.Also, s=n+10-r where s may be greater than or equal to 0. Here, thecondition may be an example, and another condition may be set.

When s=0, w=0. When s>0, w may be obtained by left shifting 1 by(s−1)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=A×X may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

An eleventh embodiment is described below.

During an actual transform process, a size of a transformation targetdata block X may be 32×8 and a data bit-width of the data block X may ben-bit. A transform matrix A may be an 8×8 matrix that satisfies acondition of J(A)<TH described in the first embodiment. In this case, itmay be required that a data bit-width of a transformed data block Y doesnot exceed r-bit. The transform process is described below.

A matrix Y may be determined by multiplying a matrix X by atransposed-matrix A. For example, Y=X×ÂT may be set. In order to obtaina result, w may be added to each element of the matrix Y. The resultexpressed in the form of a natural binary may be shifted right by s-bitso as to obtain a result of transformation. Also, s=n+10-r where s maybe greater than or equal to 0. Here, the condition may be an example,and another condition may be set.

When s<0, w=0. When s≥0, w may be obtained by left shifting 1 by(s−2)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=X×ÂT may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

A twelfth embodiment is described below.

During an actual transform process, a size of a transformation targetdata block X may be 32×4 and a data bit-width of the data block X may ben-bit. A transform matrix A may be a 4×4 matrix that satisfies acondition of J(A)<TH described in the fourth embodiment. In this case,it may be required that a data bit-width of a transformed data block Ydoes not exceed r-bit. The transform process is described below.

A matrix Y may be determined by multiplying a matrix X by a matrix A.For example, Y=X×A may be set. In order to obtain a result, w may beadded to each element of the matrix Y. The result expressed in the formof a natural binary may be shifted right by s-bit so as to obtain aresult of transformation. Also, s=n+7−r where s may be greater than orequal to 0. Here, the condition may be an example, and another conditionmay be set.

w may be obtained by rounding a result obtained by left shifting 1 bys-bit and then being divided by 3, in which 1 is expressed in the formof a natural binary.

The transform process Y=X×A may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

A thirteenth embodiment is described below.

During an actual transform process, a size of a transformation targetdata block X may be 32×8 and a data bit-width of the data block X may ben-bit. A transform matrix A may be a 32×32 matrix that satisfies acondition of J(A)<TH described in the sixth embodiment. In this case, itmay be required that a data bit-width of a transformed data block Y doesnot exceed r-bit. The transform process is described below.

A matrix Y may be determined by multiplying a transposed-matrix A by amatrix X. For example, Y=ÂT×X may be set. In order to obtain a result, wmay be added to each element of the matrix Y. The result expressed inthe form of a natural binary may be shifted right by s-bit so as toobtain a result of transformation. Also, s=n+6−r where s may be greaterthan or equal to 0. Here, the condition may be an example, and anothercondition may be set.

w may be obtained by rounding a result obtained by left shifting 1 bys-bit and then being divided by 6, in which 1 is expressed in the formof a natural binary.

The transform process Y=ÂT×X may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

A fourteenth embodiment is described below.

In video image coding, when a reconstructed residual is used during areconstruction process of an image, a bit-width of the reconstructedresidual may be n-bit. It may be required that a bit-width ofintermediate data does not exceed r-bit during a transformation process.For an N×N block, a corresponding reconstructed residual block may be Cthat is obtained by performing two-dimensional N×N inverse transform toan inverse-quantized coefficient block X (a data bit-width of the blockX may be s0). As described in the aforementioned embodiments, thetransform matrix that satisfies J(A)<TH may be the matrix A. Theinverse-transform may include following operations.

In operation 1, a first-dimensional inverse-transform may be performedon X so as to obtain a result, and then the result may be shifted rightby s1-bit so as to obtain Y1.

For example, formula (14) may be satisfied.

Y1=(X×A+(1<<(s1−1)))>>s1  [formula (14)]

Hereinafter, the meaning of formula (14) is described. In Y=X×A, w1 maybe added to each element in a matrix Y so as to obtain a result, and theresult that is expressed in the form of a natural binary may be shiftedright by s1-bit so as to obtain a transform result Y1. When s1=0, w1=0,and when s1>0, w1 may be a result obtained by left shifting 1 by(s1-1)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=X×A may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

In operation 2, a second-dimensional inverse transform may be performedon Y1 so as to obtain a result, and then the result may be shifted rightby s2-bit so as to obtain C.

For example, formula (15) may be satisfied.

C=(ÂT×Y1+(1<<(s2−1)))>>s2  [formula (15)]

Hereinafter, the meaning of formula (15) is described. In Y=ÂT×Y1, w2may be added to each element in a matrix Y so as to obtain a result, andthe result that is expressed in the form of a natural binary may beshifted right by s1-bit so as to obtain a transform result C. When s2=0,w2=0, and when s2>0, w2 may be a result obtained by left shifting 1 by(s1-1)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=ÂT×Y1 may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

An intermediate value m may be defined by using formula (16).

m=log₂(Factor/√{square root over (N)})  [formula (16)]

In a limitation condition of a transform matrix A, values of s1 and s2may satisfy s1=s0+M−r, s2=r+m−n, s1≥0 and s2≥0.

During the process described above, the symbol “<<” may indicate to leftshift data that is expressed in the form of a natural binary, and thesymbol “>>” may indicate to right shift data that is expressed in theform of a natural binary.

A fifteenth embodiment is described below.

In video image coding, a prediction residual may be obtained whenprediction coding is performed on pixels. A bit-width of the predictionresidual may be n-bit. It may be required that a bit-width ofintermediate data during the transform process does not exceed r-bit. Atwo-dimensional N×N forward transform may be performed on an N×Nresidual block X. As described in the aforementioned embodiments, atransform matrix that satisfies J(A)<TH may be the matrix A. Thetransform may include following operations.

In operation 1, a first-dimensional forward-transform may be performedon X so as to obtain a result, and then the result may be shifted rightby s1-bit so as to obtain Y1.

For example, formula (17) may be satisfied.

Y1=(X×A+(1<<(s1−2)))>>s1  [formula (17)]

Hereinafter, the meaning of formula (17) is described. In Y=X×A, w1 maybe added to each element in a matrix Y so as to obtain a result, and theresult that is expressed in the form of a natural binary may be shiftedright by s1-bit so as to obtain a transform result Y1. When S1<2, w1=0,and when s1≥2, w1 may be a result obtained by left shifting 1 by(s1−2)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=X×A may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

In operation 2, a second-dimensional forward transform may be performedon Y1 so as to obtain a result, and then the result may be shifted rightby s2-bit so as to obtain Y2.

For example, formula (18) may be satisfied.

Y2=(Y1×ÂT+(1<<(s2−1)))>>s2  [formula (18)]

Hereinafter, the meaning of formula (18) is described. In Y=Y1×ÂT, w2may be added to each element in a matrix Y so as to obtain a result, andthe result that is expressed in the form of a natural binary may beshifted right by s1-bit so as to obtain a transform result Y2. Whens2=0, w2=0, and when s2>0, w2 may be a result obtained by left shifting1 by (s2−1)-bit, in which 1 is expressed in the form of a naturalbinary.

The transform process Y=Y1×ÂT may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

Intermediate values m1 and m2 may be defined by using formulas (19) and(20).

m1=log₂(Factor/√{square root over (N)})  [formula (19)]

m2=log₂(N)  [formula (20)]

In a limitation condition of a transform matrix A, values of s1 and s2may satisfy s1=n+m1+m2−r, s2=m1+m2, s1≥0 and s2≥0.

During the process described above, the symbol “<<” may indicate to leftshift data that is expressed in the form of a natural binary, and thesymbol “>>” may indicate to right shift data that is expressed in theform of a natural binary.

A sixteenth embodiment is described below.

In video image coding, when a reconstructed residual is used during areconstruction process of an image, a bit-width of the reconstructedresidual may be n-bit. It may be required that a bit-width ofintermediate data does not exceed r-bit during a transform process. Foran N×N block, a corresponding reconstructed residual block may be C thatis obtained by performing two-dimensional N×N inverse-transform on aninverse-quantized coefficient block X (a data bit-width of the block Xmay be s0). As described in the aforementioned embodiments, thetransform matrix that satisfies J(A)<TH may be the matrix A. Theinverse-transform may include following operations.

In operation 1, a first-dimensional inverse-transform may be performedon X so as to obtain a result, and then the result may be shifted rightby s1-bit so as to obtain Y1.

For example, the aforementioned formula (14) may be satisfied.

Hereinafter, the meaning of formula (14) is described. In Y=X×A, w1 maybe added to each element in a matrix Y so as to obtain a result, and theresult that is expressed in the form of a natural binary may be shiftedright by s1-bit so as to obtain a transform result Y1. When s1=0, w1=0,and when s1>0, w1 may be a result obtained by left shifting 1 by(s1−1)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=X×A may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

In operation 2, a second-dimensional inverse transform may be performedon Y1 so as to obtain a result, and then the result may be shifted rightby s2-bit so as to obtain C.

For example, the aforementioned formula (15) may be satisfied.

Hereinafter, the meaning of formula (15) is described. In Y=ÂT×Y1, w2may be added to each element in a matrix Y so as to obtain a result, andthe result that is expressed in the form of a natural binary may beshifted right by s1-bit so as to obtain a transform result C. When s2=0,w2=0, and when s2≥0, w2 may be a result obtained by left shifting 1 by(s2−1)-bit, in which 1 is expressed in the form of a natural binary.

The transform process Y=ÂT×Y1 may be expressed by matrix multiplication,while in practice, the matrix multiplication may be implemented with abutterfly structure.

An intermediate value m may be defined by using the aforementionedformula (16).

In the limitation condition of the transform matrix A, the values of s1and s2 may satisfy s1=s0+M−r, s2=r+m-n, s1≥0 and s2≥0.

During the process described above, the symbol “<<” may indicate to leftshift data that is expressed in the form of a natural binary, and thesymbol “>>” may indicate to right shift data that is expressed in theform of a natural binary.

As shown in FIG. 6N, the device 10 may determine a transform coefficientof a transformation unit by using a transform matrix configured of {{32,32, 32, 32}, {42, 17, −17, −42}, {32, −32, −32, 32}, {17, −42, 42,−17}}. When an element in the n-th row of m-th column of a matrix isexpressed as a_mn, a 4×4 matrix may be expressed as {{a_11, a_12, a_13,a_14}, {a_21, a_22, a_23, a_24}, {a_31, a_32, a_33, a_34}, {a_41, a_42,a_43, a_44}}. A matrix other than the 4×4 matrix may be expressed in asame manner. As another example, a 2×2 matrix may be expressed as {{a11, a_12}, {a_21, a_22}}.

The device 10 may determine at least one transform unit to performtransformation on a residual in a coding unit. Here, the device 10 maydetermine a transform coefficient of a transformation unit by using atransform matrix configured of {{32, 32, 32, 32}, {42, 17, −17, −42},{32, −32, −32, 32}, {17, −42, 42, −17}}.

Also, the element may have a value that is greater than an element of aminimum-value matrix and less than an element of a maximum-value matrix,wherein the minimum-value matrix is configured of elements of minimumvalue and the maximum-value matrix is configured of elements of maximumvalue which are used in a frequency transform. Here, in the transformmatrix, a result value of a function indicating at least one selectedfrom transform distortion, normalization, and orthogonality of thetransform matrix may be less than a predetermined maximum thresholdvalue.

FIG. 6N is an exemplary embodiment, and descriptions regarding FIG. 6Nmay be applied to all diagrams of FIG. 6. For example, the device 10 mayperform the frequency transform by using matrices shown in FIGS. 6J, 6K,6L, and 6M. Here, the matrices shown in FIGS. 6J, 6K, 6L, and 6M may beregarded as transform matrices, transform coefficients of the transformmatrices may be determined, and detailed contents are described withreference to FIG. 6N.

FIG. 7 illustrates a block diagram of the device 10, according tovarious embodiments.

The device 10 may be a device capable of performing the aforementionedsignal transforming method, and implementation of all embodiments ofperforming the aforementioned signal transforming method is possible.

As shown in FIG. 7, the device 10 may include a range determiner 71, amaximum threshold value determiner 72, a transform matrix determiner 73,and a transformer 74. However, the device 10 may be embodied with moreelements than the shown elements or may be embodied with fewer elementsthan the shown elements.

Hereinafter, the elements are sequentially described below.

The range determiner 71 may determine a minimum-value matrix and amaximum-value matrix with respect to elements of a matrix used infrequency transformation, wherein the minimum-value matrix is configuredof the elements of minimum value and the maximum-value matrix isconfigured of the elements of maximum value.

In addition, the range determiner 71 may determine, based on a size ofthe matrix, a DCT matrix that is a matrix used in a DCT transform, andmay determine, by using the determined DCT matrix, the minimum-valuematrix and the maximum-value matrix which are configured of integerelements. The DCT matrix may include irrational elements.

In addition, the range determiner 71 may determine the minimum-valuematrix as a matrix including element values obtained by multiplying eachof elements of the determined DCT matrix by a predetermined factor,rounding multiplication results of the multiplying, and then subtractinga predetermined value from results of the rounding, and may determinethe maximum-value matrix as a matrix including element values obtainedby multiplying each of the elements of the determined DCT matrix by thepredetermined factor, rounding the results of the multiplying, and thenadding the predetermined value to the results of the rounding.

The maximum threshold value determiner 72 may determine a maximumthreshold value of a result value of a function indicating at least oneselected from transform distortion, normalization, and orthogonality ofthe matrix.

In addition, the maximum threshold value determiner 72 may determine areference matrix including the element values obtained by multiplyingeach of the elements of the determined DCT matrix by the predeterminedfactor, and rounding the results of the multiplying, may determine areference matrix function value that is a result value of a functionindicating at least one selected from transform distortion,normalization, and orthogonality of the reference matrix, and maydetermine the reference matrix function value as the maximum thresholdvalue.

In addition, the maximum threshold value determiner 72 may determine areference matrix that is a matrix configured of integer elements, basedon a method defined in H.265, may determine a reference matrix functionvalue that is a result value of a function indicating at least oneselected from transform distortion, normalization, and orthogonality ofthe reference matrix, and may determine the reference matrix functionvalue as the maximum threshold value.

In addition, the maximum threshold value determiner 72 may determine themaximum threshold value by multiplying a number of rows of the transformmatrix by a predetermined value.

The transform matrix determiner 73 may determine a transform matrixconfigured of elements that are greater than the elements of theminimum-value matrix and less than the elements of the maximum-valuematrix at respective positions of the matrix, and in which the resultvalue of the function is less than the maximum threshold value.

The transformer 74 may transform an input signal by using the determinedtransform matrix.

In addition, the transformer 74 may determine an input matrix that is amatrix with respect to the input signal, and may perform an operation onthe determined transform matrix and the input matrix, and thus maydetermine an output matrix that is a matrix with respect to an outputsignal.

In addition, the transformer 74 may determine a matrix transposed fromthe determined transform matrix, and may perform an operation on thematrix transposed from the determined transform matrix and the inputmatrix, and thus may determine an output matrix that is a matrix withrespect to an output signal.

The embodiments described above with reference to FIG. 7 are onlyexemplary embodiments, and it will be understood by one of ordinaryskill in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the presentinvention.

FIG. 8 illustrates a block diagram of a video encoding apparatus basedon coding units of a tree structure 100, according to an embodiment ofthe present invention.

The video encoding apparatus involving video prediction based on codingunits of the tree structure 100 includes a coding unit determiner 120and an output unit 130.

Hereinafter, for convenience of description, the video encodingapparatus involving video prediction based on coding units of the treestructure 100 is referred as ‘video encoding apparatus 100’.

The coding unit determiner 120 may split a current picture based on alargest coding unit that is a coding unit having a maximum size for acurrent picture of an image. If the current picture is larger than thelargest coding unit, image data of the current picture may be split intothe at least one largest coding unit. The largest coding unit accordingto an embodiment may be a data unit having a size of 32×32, 64×64,128×128, 256×256, etc., wherein a shape of the data unit is a squarehaving a width and length in squares of 2.

A coding unit according to an embodiment may be characterized by amaximum size and a depth. The depth denotes the number of times thecoding unit is spatially split from the largest coding unit, and as thedepth deepens, deeper coding units according to depths may be split fromthe largest coding unit to a minimum coding unit. A depth of the largestcoding unit is an uppermost depth and a depth of the minimum coding unitis a lowermost depth. Since a size of a coding unit corresponding toeach depth decreases as the depth of the largest coding unit deepens, acoding unit corresponding to an upper depth may include a plurality ofcoding units corresponding to lower depths.

As described above, the image data of the current picture is split intothe largest coding units according to a maximum size of the coding unit,and each of the largest coding units may include deeper coding unitsthat are split according to depths. Since the largest coding unitaccording to an embodiment is split according to depths, the image dataof a spatial domain included in the largest coding unit may behierarchically classified according to depths.

A maximum depth and a maximum size of a coding unit, which limit thetotal number of times a height and a width of the largest coding unitare hierarchically split, may be predetermined.

The coding unit determiner 120 encodes at least one split regionobtained by splitting a region of the largest coding unit according todepths, and determines a depth to output a finally encoded image dataaccording to the at least one split region. In other words, the codingunit determiner 120 determines a final depth by encoding the image datain the deeper coding units according to depths, according to the largestcoding unit of the current picture, and selecting a depth having theleast encoding error. The determined final depth and the encoded imagedata according to the determined final depth are output to the outputunit 130.

The image data in the largest coding unit is encoded based on the deepercoding units corresponding to at least one depth equal to or below themaximum depth, and results of encoding the image data are compared basedon each of the deeper coding units. A depth having the least encodingerror may be selected after comparing encoding errors of the deepercoding units. At least one final depth may be determined for eachlargest coding unit.

The size of the largest coding unit is split as a coding unit ishierarchically split according to depths, and as the number of codingunits increases. Also, even if coding units correspond to the same depthin one largest coding unit, it is determined whether to split each ofthe coding units corresponding to the same depth to a lower depth bymeasuring an encoding error of the image data of the each coding unit,separately. Accordingly, even when image data is included in one largestcoding unit, the encoding errors may differ according to regions in theone largest coding unit, and thus the final depths may differ accordingto regions in the image data. Thus, one or more final depths may be setin one largest coding unit, and the image data of the largest codingunit may be divided according to coding units of at least one finaldepth.

Accordingly, the coding unit determiner 120 may determine coding unitshaving a tree structure included in the largest coding unit. The ‘codingunits having a tree structure’ according to an embodiment include codingunits corresponding to a depth determined to be the final depth, fromamong all deeper coding units included in the largest coding unit. Acoding unit of a final depth may be hierarchically determined accordingto depths in the same region of the largest coding unit, and may beindependently determined in different regions. Similarly, a final depthin a current region may be independently determined from a final depthin another region.

A maximum depth according to an embodiment is an index related to thenumber of splitting times from a largest coding unit to a minimum codingunit. A first maximum depth according to an embodiment may denote thetotal number of splitting times from the largest coding unit to theminimum coding unit. A second maximum depth according to an embodimentmay denote the total number of depth levels from the largest coding unitto the minimum coding unit. For example, when a depth of the largestcoding unit is 0, a depth of a coding unit, in which the largest codingunit is split once, may be set to 1, and a depth of a coding unit, inwhich the largest coding unit is split twice, may be set to 2. Here, ifthe minimum coding unit is a coding unit in which the largest codingunit is split four times, 5 depth levels of depths 0, 1, 2, 3, and 4exist, and thus the first maximum depth may be set to 4, and the secondmaximum depth may be set to 5.

Prediction encoding and transformation may be performed according to thelargest coding unit. The prediction encoding and the transformation arealso performed based on the deeper coding units according to a depthequal to or depths less than the maximum depth, according to the largestcoding unit.

Since the number of deeper coding units increases whenever the largestcoding unit is split according to depths, encoding, including theprediction encoding and the transformation, is performed on all of thedeeper coding units generated as the depth deepens. For convenience ofdescription, the prediction encoding and the transformation will now bedescribed based on a coding unit of a current depth, in a largest codingunit.

The video encoding apparatus 100 according to the present embodiment mayvariously select a size or shape of a data unit for encoding the imagedata. In order to encode the image data, operations, such as predictionencoding, transformation, and entropy encoding, are performed, and atthis time, the same data unit may be used for all operations ordifferent data units may be used for each operation.

For example, the video encoding apparatus 100 may select not only acoding unit for encoding the image data, but also a data unit differentfrom the coding unit so as to perform the prediction encoding on theimage data in the coding unit.

In order to perform prediction encoding in the largest coding unit, theprediction encoding may be performed based on a coding unitcorresponding to a final depth, i.e., based on a coding unit that is nolonger split into coding units corresponding to a lower depth.Hereinafter, the coding unit that is no longer split and becomes a basisunit for prediction encoding will now be referred to as a ‘predictionunit’. A partition obtained by splitting the prediction unit may includea prediction unit or a data unit obtained by splitting at least oneselected from a height and a width of the prediction unit. A partitionis a data unit where a prediction unit of a coding unit is split, and aprediction unit may be a partition having the same size as a codingunit.

For example, when a coding unit of 2N×2N (where N is a positive integer)is no longer split and becomes a prediction unit of 2N×2N, and a size ofa partition may be 2N×2N, 2N×N, N×2N, or N×N. Examples of a partitionmode may selectively include symmetrical partitions that are obtained bysymmetrically splitting a height or width of the prediction unit,partitions obtained by asymmetrically splitting the height or width ofthe prediction unit, such as 1:n or n:1, partitions that are obtained bygeometrically splitting the prediction unit, and partitions havingarbitrary shapes.

A prediction mode of the prediction unit may be at least one selectedfrom an intra mode, a inter mode, and a skip mode. For example, theintra mode or the inter mode may be performed on the partition of 2N×2N,2N×N, N×2N, or N×N. Also, the skip mode may be performed only on thepartition of 2N×2N. The encoding is independently performed on oneprediction unit in a coding unit, thereby selecting a prediction modehaving a least encoding error.

The video encoding apparatus 100 may also perform the transformation onthe image data in a coding unit based not only on the coding unit forencoding the image data, but also based on a data unit that is differentfrom the coding unit. In order to perform the transformation in thecoding unit, the transformation may be performed based on a data unithaving a size smaller than or equal to the coding unit. For example, thedata unit for the transformation may include a data unit for an intramode and a data unit for an inter mode.

The transformation unit in the coding unit may be recursively split intosmaller sized regions in the similar manner as the coding unit accordingto the tree structure. Thus, residual data in the coding unit may bedivided according to the transformation unit having the tree structureaccording to transformation depths.

A transformation depth indicating the number of splitting times to reachthe transformation unit by splitting the height and width of the codingunit may also be set in the transformation unit. For example, in acurrent coding unit of 2N×2N, a transformation depth may be 0 when thesize of a transformation unit is 2N×2N, may be 1 when the size of thetransformation unit is N×N, and may be 2 when the size of thetransformation unit is N/2×N/2. In other words, the transformation unithaving the tree structure may be set according to the transformationdepths.

Split information according to depths requires not only informationabout depths, but also about information related to prediction encodingand transformation. Accordingly, the coding unit determiner 120 not onlydetermines a depth having a least encoding error, but also determines apartition mode in a prediction unit, a prediction mode according toprediction units, and a size of a transformation unit fortransformation.

Coding units according to a tree structure in a largest coding unit andmethods of determining a prediction unit/partition, and a transformationunit, according to embodiments, will be described in detail later withreference to FIGS. 9 through 19.

The coding unit determiner 120 may measure an encoding error of deepercoding units according to depths by using Rate-Distortion Optimizationbased on Lagrangian multipliers.

The output unit 130 outputs the image data of the largest coding unit,which is encoded based on the at least one depth determined by thecoding unit determiner 120, and the split information according todepths, in bitstreams.

The encoded image data may be obtained by encoding residual data of animage.

The split information according to depths may include depth information,information about the partition mode in the prediction unit, informationabout the prediction mode, split information of the transformation unit,or the like.

The information about the final depth may be defined by using splitinformation according to depths, which indicates whether encoding isperformed on coding units of a lower depth instead of a current depth.If the current depth of the current coding unit is the depth, image datain the current coding unit is encoded and output, and thus the splitinformation may be defined not to split the current coding unit to alower depth. Alternatively, if the current depth of the current codingunit is not the depth, the encoding is performed on the coding unit ofthe lower depth, and thus the split information may be defined to splitthe current coding unit to obtain the coding units of the lower depth.

If the current depth is not the depth, encoding is performed on thecoding unit that is split into the coding unit of the lower depth. Sinceat least one coding unit of the lower depth exists in one coding unit ofthe current depth, the encoding is repeatedly performed on each codingunit of the lower depth, and thus the encoding may be recursivelyperformed for the coding units having the same depth.

Since the coding units having a tree structure are determined for onelargest coding unit, and split information is determined for a codingunit of a depth, split information may be determined for one largestcoding unit. Also, data of the largest coding unit may be hierarchicallysplit according to depths, and thus a depth of the data may be differentaccording to locations, so that the depth and the split information maybe set for the data.

Accordingly, the output unit 130 according to the present embodiment mayassign encoding information about a corresponding depth and an encodingmode to at least one selected from the coding unit, the prediction unit,and a minimum unit included in the largest coding unit.

The minimum unit according to an embodiment is a square data unitobtained by splitting the minimum coding unit constituting the lowermostdepth by 4. Alternatively, the minimum unit according to an embodimentmay be a maximum square data unit that may be included in all of thecoding units, prediction units, partition units, and transformationunits included in the largest coding unit.

For example, the encoding information output by the output unit 130 maybe classified into encoding information according to deeper codingunits, and encoding information according to prediction units. Theencoding information according to the deeper coding units may includethe information about the prediction mode and about the size of thepartitions. The encoding information according to the prediction unitsmay include information about an estimated direction during an intermode, about a reference image index of the inter mode, about a motionvector, about a chroma component of an intra mode, and about aninterpolation method during the intra mode.

Information about a maximum size of the coding unit defined according topictures, slices, or GOPs, and information about a maximum depth may beinserted into a header of a bitstream, a sequence parameter set, or apicture parameter set.

Information about a maximum size of the transformation unit permittedwith respect to a current video, and information about a minimum size ofthe transformation unit may also be output through a header of abitstream, a sequence parameter set, or a picture parameter set. Theoutput unit 130 may encode and output reference information, predictioninformation, and slice type information that are related to prediction.

According to the simplest embodiment for the video encoding apparatus100, the deeper coding unit may be a coding unit obtained by dividing aheight or width of a coding unit of an upper depth, which is one layerabove, by two. In other words, when the size of the coding unit of thecurrent depth is 2N×2N, the size of the coding unit of the lower depthis N×N. Also, the coding unit with the current depth having a size of2N×2N may include a maximum of 4 of the coding units with the lowerdepth.

Accordingly, the video encoding apparatus 100 may form the coding unitshaving the tree structure by determining coding units having an optimumshape and an optimum size for each largest coding unit, based on thesize of the largest coding unit and the maximum depth determinedconsidering characteristics of the current picture. Also, since encodingmay be performed on each largest coding unit by using any one of variousprediction modes and transformations, an optimum encoding mode may bedetermined considering characteristics of the coding unit of variousimage sizes.

Thus, if an image having a high resolution or a large data amount isencoded in a conventional macroblock, the number of macroblocks perpicture excessively increases.

Accordingly, the number of pieces of compressed information generatedfor each macroblock increases, and thus it is difficult to transmit thecompressed information and data compression efficiency decreases.However, by using the video encoding apparatus 100 according to thepresent embodiment, image compression efficiency may be increased sincea coding unit is adjusted while considering characteristics of an imagewhile increasing a maximum size of a coding unit while considering asize of the image.

The device 10 described above with reference to FIG. 1 may include thevideo encoding apparatuses 100 corresponding to the number of layers soas to encode single layer images in each of the layers of a multilayervideo. For example, a first layer encoder 12 may include one videoencoding apparatus 100, and a second layer encoder 14 may include thevideo encoding apparatuses 100 corresponding to the number of secondlayers.

When the video encoding apparatuses 100 encode first layer images, thecoding unit determiner 120 may determine a prediction unit forinter-image prediction for each of coding units of a tree structureaccording to each largest coding unit, and may perform the inter-imageprediction on each prediction unit.

When the video encoding apparatuses 100 encode second layer images, thecoding unit determiner 120 may determine prediction units and codingunits of a tree structure according to each largest coding unit, and mayperform inter-prediction on each of the prediction units.

The video encoding apparatuses 100 may encode a luminance differencebetween the first layer image and the second layer image so as tocompensate for the luminance difference. However, whether or not toperform luminance may be determined according to a coding mode of acoding unit. For example, luminance compensation may be performed onlyon a prediction unit having a size of 2N×2N.

FIG. 9 illustrates a block diagram of a video decoding apparatus basedon coding units of a tree structure 200, according to variousembodiments.

The video decoding apparatus involving video prediction based on codingunits of the tree structure 200 according to the present embodimentincludes a receiver 210, an image data and encoding informationextractor 220, and an image data decoder 230. Hereinafter, forconvenience of description, the video decoding apparatus involving videoprediction based on coding units of the tree structure 200 according tothe embodiment is referred as ‘video decoding apparatus 200’.

Definitions of various terms, such as a coding unit, a depth, aprediction unit, a transformation unit, and various split information,for decoding operations of the video decoding apparatus 200 according tothe present embodiment are identical to those described with referenceto FIG. 8 and the video encoding apparatus 100.

The receiver 210 receives and parses a bitstream of an encoded video.The image data and encoding information extractor 220 extracts encodedimage data for each coding unit from the parsed bitstream, wherein thecoding units have a tree structure according to each largest codingunit, and outputs the extracted image data to the image data decoder230. The image data and encoding information extractor 220 may extractinformation about a maximum size of a coding unit of a current picture,from a header about the current picture, a sequence parameter set, or apicture parameter set.

Also, the image data and encoding information extractor 220 extracts afinal depth and split information with respect to the coding unitshaving a tree structure according to each largest coding unit, from theparsed bitstream. The extracted final depth and the split informationare output to the image data decoder 230. That is, the image data in abit stream is split into the largest coding unit so that the image datadecoder 230 decodes the image data for each largest coding unit.

The depth and the split information according to the largest coding unitmay be set for information about at least one coding unit correspondingto the depth, and split information according to depths may includepartition mode information of a corresponding coding unit, predictionmode information, and split information of a transformation unit. Also,splitting information may be extracted as the information about thedepth.

The depth and the split information according to each largest codingunit extracted by the image data and encoding information extractor 220is information about a depth and split information determined togenerate a minimum encoding error when an encoder, such as the videoencoding apparatus 100, repeatedly performs encoding for each deepercoding unit according to depths according to each largest coding unit.Accordingly, the video decoding apparatus 200 may reconstruct an imageby decoding the image data according to a final depth and an encodingmode that generates the minimum encoding error.

Since encoding information about the depth and the encoding mode may beassigned to a predetermined data unit from among a corresponding codingunit, a prediction unit, and a minimum unit, the image data and encodinginformation extractor 220 may extract a depth and split informationaccording to the predetermined data units. If information about a depthand split of a corresponding largest coding unit is recorded accordingto predetermined data units, the predetermined data units having thesame information about depth and split may be inferred to be the dataunits included in the same largest coding unit.

The image data decoder 230 reconstructs the current picture by decodingthe image data in each largest coding unit based on the informationabout depth and split according to the largest coding units. In otherwords, the image data decoder 230 may decode the encoded image databased on the extracted information about the partition mode, theprediction mode, and the transformation unit for each coding unit fromamong the coding units having the tree structure included in eachlargest coding unit. A decoding process may include a predictionincluding intra prediction and motion compensation, and an inversetransformation.

The image data decoder 230 may perform intra prediction or motioncompensation according to a partition and a prediction mode of eachcoding unit, based on the information about the partition mode and theprediction mode of the prediction unit of the coding unit according todepths.

In addition, the image data decoder 230 may read information about atransformation unit according to a tree structure for each coding unitso as to perform inverse transformation based on transformation unitsfor each coding unit, for inverse transformation for each largest codingunit. Via the inverse transformation, a pixel value of a spatial domainof the coding unit may be reconstructed.

The image data decoder 230 may determine a depth of a current largestcoding unit by using split information according to depths. If the splitinformation indicates that image data is no longer split in the currentdepth, the current depth is a depth. Accordingly, the image data decoder230 may decode encoded data in the current largest coding unit by usingthe information about the partition mode of the prediction unit, theprediction mode, and the size of the transformation unit for each codingunit corresponding to the final depth.

In other words, data units containing the encoding information includingthe same split information may be gathered by observing the encodinginformation set assigned for the predetermined data unit from among thecoding unit, the prediction unit, and the minimum unit, and the gathereddata units may be considered to be one data unit to be decoded by theimage data decoder 230 in the same encoding mode. As such, the currentcoding unit may be decoded by obtaining the information about theencoding mode for each coding unit.

Also, the device 10 described above with reference to FIG. 1 may includethe video decoding apparatuses 200 corresponding to the number of views,so as to decode a received first layer image stream and a receivedsecond layer image stream and to reconstruct first layer images andsecond layer images.

When the first layer image stream is received, the image data decoder230 of the video decoding apparatus 200 may split samples of the firstlayer images, which are extracted from the first layer image stream byan extractor 220, into coding units according to a tree structure of alargest coding unit. The image data decoder 230 may perform motioncompensation, based on prediction units for the inter-image prediction,on each of the coding units according to the tree structure of thesamples of the first layer images, and may reconstruct the first layerimages.

When the second layer image stream is received, the image data decoder230 of the video decoding apparatus 200 may split samples of the secondlayer images, which are extracted from the second layer image stream bythe extractor 220, into coding units according to a tree structure of alargest coding unit. The image data decoder 230 may perform motioncompensation, based on prediction units for the inter-image prediction,on each of the coding units of the samples of the second layer images,and may reconstruct the second layer images.

The extractor 220 may obtain, from the bitstream, information related toa luminance error so as to compensate for the luminance differencebetween the first layer image and the second layer image. However,whether or not to perform luminance may be determined according to acoding mode of a coding unit. For example, luminance compensation may beperformed only on a prediction unit having a size of 2N×2N.

Thus, the video decoding apparatus 200 may obtain information about atleast one coding unit that generates the minimum encoding error whenencoding is recursively performed for each largest coding unit, and mayuse the information to decode the current picture. That is, the codingunits having the tree structure determined to be the optimum codingunits in each largest coding unit may be decoded.

Accordingly, even if an image has high resolution or has an excessivelylarge data amount, the image may be efficiently decoded andreconstructed by using a size of a coding unit and an encoding mode,which are adaptively determined according to characteristics of theimage, by using optimal split information received from an encoder.

FIG. 10 illustrates a diagram for describing a concept of coding unitsaccording to various embodiments.

A size of a coding unit may be expressed by width×height, and may be64×64, 32×32, 16×16, and 8×8. A coding unit of 64×64 may be split intopartitions of 64×64, 64×32, 32×64, or 32×32, and a coding unit of 32×32may be split into partitions of 32×32, 32×16, 16×32, or 16×16, a codingunit of 16×16 may be split into partitions of 16×16, 16×8, 8×16, or 8×8,and a coding unit of 8×8 may be split into partitions of 8×8, 8×4, 4×8,or 4×4.

In video data 310, a resolution is 1920×1080, a maximum size of a codingunit is 64, and a maximum depth is 2. In video data 320, a resolution is1920×1080, a maximum size of a coding unit is 64, and a maximum depth is3. In video data 330, a resolution is 352×288, a maximum size of acoding unit is 16, and a maximum depth is 1. The maximum depth shown inFIG. 10 denotes the total number of splits from a largest coding unit toa minimum decoder.

If a resolution is high or a data amount is large, a maximum size of acoding unit may be large so as to not only increase encoding efficiencybut also to accurately reflect characteristics of an image. Accordingly,the maximum size of the coding unit of the video data 310 and 320 havinga higher resolution than the video data 330 may be 64.

Since the maximum depth of the video data 310 is 2, coding units 315 ofthe vide data 310 may include a largest coding unit having a long axissize of 64, and coding units having long axis sizes of 32 and 16 sincedepths are deepened to two layers by splitting the largest coding unittwice. On the other hand, since the maximum depth of the video data 330is 1, coding units 335 of the video data 330 may include a largestcoding unit having a long axis size of 16, and coding units having along axis size of 8 since depths are deepened to one layer by splittingthe largest coding unit once.

Since the maximum depth of the video data 320 is 3, coding units 325 ofthe video data 320 may include a largest coding unit having a long axissize of 64, and coding units having long axis sizes of 32, 16, and 8since the depths are deepened to 3 layers by splitting the largestcoding unit three times. As a depth deepens, an expression capabilitywith respect to detailed information may be improved.

FIG. 11 illustrates a block diagram of an image encoder 400 based oncoding units, according to various embodiments.

The image encoder 400 according to the embodiment performs operations ofthe video encoding apparatus 100 to encode image data. That is, an intrapredictor 420 performs intra prediction on a coding unit in an intramode and from among a current image 405, according to prediction units,and an inter predictor 415 performs inter prediction on a coding unit inan inter mode according to prediction units, by using a reference imageobtained from the current image 405 and a reconstructed picture buffer410. The current image 405 may be split by a largest coding unit and maybe sequentially encoded. Here, encoding may be performed on coding unitsof a tree structure, which are split from the largest coding unit.

Prediction data with respect to the coding unit in each mode output fromthe intra predictor 420 or the inter predictor 415 is subtracted fromdata with respect to an encoded coding unit of the current image 405, sothat residue data is generated. The residue data is output as aquantized transformation coefficient of each transformation unit througha transformer 425 and a quantizer 430. The quantized transformationcoefficient is reconstructed as residue data of a spatial domain throughan inverse quantizer 445 and an inverse transformer 450. Thereconstructed residue data of the spatial domain is added to theprediction data with respect to the coding unit in each mode output fromthe intra predictor 420 or the inter predictor 415, and thus isreconstructed as data of the spatial domain with respect to the codingunit of the current image 405. The reconstructed data of the spatialdomain is generated as a reconstructed image through a deblocking unit455 and an SAO performer 460. The generated reconstructed image isstored in the reconstructed picture buffer 410. Reconstructed imagesstored in the reconstructed picture buffer 410 may be used as areference image for inter prediction with respect to another image. Thetransformation coefficient quantized in the transformer 425 and thequantizer 430 may be output as a bitstream 440 through an entropyencoder 435.

In order for the image encoder 400 to be applied in the video encodingapparatus 100, all elements of the image encoder 400, i.e., the interpredictor 415, the intra predictor 420, the transformer 425, thequantizer 430, the entropy encoder 435, the inverse quantizer 445, theinverse transformer 450, the deblocking unit 455, and the SAO performer460 may perform operations based on each coding unit among coding unitsaccording to a tree structure in each largest coding unit.

In particular, the intra predictor 420 and the inter predictor 415 maydetermine a partition mode and a prediction mode of each coding unitfrom among the coding units according to a tree structure by referringto a maximum size and a maximum depth of a current largest coding unit,and the transformer 425 may determine whether or not to split atransformation unit according to a quadtree in each coding unit fromamong the coding units according to the tree structure.

FIG. 12 illustrates a block diagram of an image decoder 500 based oncoding units, according to various embodiments.

An entropy decoder 515 parses, from a bitstream 505, encoded image datato be decoded and encoding information required for decoding. Theencoded image data is as a quantized transformation unit, and an inversequantizer 520 and an inverse transformer 525 reconstruct residue datafrom the quantized transformation unit.

An intra predictor 540 performs intra prediction on a coding unit in anintra mode according to prediction units. An inter predictor 535performs inter prediction by using a reference image with respect to acoding unit in an inter mode from among a current image, which isobtained by a reconstructed picture buffer 530 according to predictionunits.

Prediction data with respect to the coding unit in each mode whichpassed through the intra predictor 540 or the inter predictor 535, andthe residue data are added, so that data of a spatial domain withrespect to the coding unit of the current image 405 may bereconstructed, and the reconstructed data of the spatial domain may beoutput as a output video through a deblocking unit 545 and an SAOperformer 550.

In order for the image data decoder 230 of the video decoding apparatus200 to decode the image data, operations after the entropy decoder 515of the image decoder 500 may be sequentially performed.

In order for the image decoder 500 to be applied in the video decodingapparatus 200, all elements of the image decoder 500, i.e., the entropydecoder 515, the inverse quantizer 520, the inverse transformer 525, theintra predictor 540, the inter predictor 535, the deblocking unit 545,and the SAO performer 550 may perform operations based on each codingunit from among coding units according to a tree structure for eachlargest coding unit.

In particular, the intra predictor 540 and the inter predictor 535 maydetermine a partition mode and a prediction mode of each coding unitfrom among the coding units according to a tree structure, and theinverse transformer 525 may determine whether or not to split atransformation unit according to a quadtree in each coding unit.

The encoding operation of FIG. 10 and the decoding operation of FIG. 11are described as a videostream encoding operation and a videostreamdecoding operation, respectively, in a single layer. Therefore, if thedevice 10 of FIG. 1 encodes a videostream of at least two layers, theencoder 12 may include the image encoder 400 for each of layers.Similarly, if the decoder 26 of FIG. 10 decodes a videostream of atleast two layers, the decoder 26 may include the image decoder 500 foreach of layers.

FIG. 13 illustrates a diagram illustrating deeper coding units accordingto depths, and partitions, according to various embodiments.

The video encoding apparatus 100 according to the present embodiment andthe video decoding apparatus 200 according to the present embodiment usehierarchical coding units so as to consider characteristics of an image.A maximum height, a maximum width, and a maximum depth of coding unitsmay be adaptively determined according to the characteristics of theimage, or may be differently set by a user. Sizes of deeper coding unitsaccording to depths may be determined according to the predeterminedmaximum size of the coding unit.

In a hierarchical structure 600 of coding units, according to thepresent embodiment, the maximum height and the maximum width of thecoding units are each 64, and the maximum depth is 3. In this case, themaximum depth refers to a total number of times the coding unit is splitfrom the largest coding unit to the minimum coding unit. Since a depthdeepens along a vertical axis of the hierarchical structure 600, aheight and a width of the deeper coding unit are each split. Also, aprediction unit and partitions, which are bases for prediction encodingof each deeper coding unit, are shown along a horizontal axis of thehierarchical structure 600.

In other words, a coding unit 610 is a largest coding unit in thehierarchical structure 600, wherein a depth is 0 and a size, i.e., aheight by width, is 64×64. The depth deepens along the vertical axis,and a coding unit 620 having a size of 32×32 and a depth of 1, a codingunit 630 having a size of 16×16 and a depth of 2, and a coding unit 640having a size of 8×8 and a depth of 3. The coding unit 640 having thesize of 8×8 and the depth of 3 is a minimum coding unit.

The prediction unit and the partitions of a coding unit are arrangedalong the horizontal axis according to each depth. In other words, ifthe coding unit 610 having a size of 64×64 and a depth of 0 is aprediction unit, the prediction unit may be split into partitionsinclude in the encoder 610, i.e. a partition 610 having a size of 64×64,partitions 612 having the size of 64×32, partitions 614 having the sizeof 32×64, or partitions 616 having the size of 32×32.

Similarly, a prediction unit of the coding unit 620 having the size of32×32 and the depth of 1 may be split into partitions included in thecoding unit 620, i.e. a partition 620 having a size of 32×32, partitions622 having a size of 32×16, partitions 624 having a size of 16×32, andpartitions 626 having a size of 16×16.

Similarly, a prediction unit of the coding unit 630 having the size of16×16 and the depth of 2 may be split into partitions included in thecoding unit 630, i.e. a partition having a size of 16×16 included in thecoding unit 630, partitions 632 having a size of 16×8, partitions 634having a size of 8×16, and partitions 636 having a size of 8×8.

Similarly, a prediction unit of the coding unit 640 having the size of8×8 and the depth of 3 may be split into partitions included in thecoding unit 640, i.e. a partition having a size of 8×8 included in thecoding unit 640, partitions 642 having a size of 8×4, partitions 644having a size of 4×8, and partitions 646 having a size of 4×4.

In order to determine the at least one final depth of the coding unitsconstituting the largest coding unit 610, the coding unit determiner 120of the video encoding apparatus 100 performs encoding for coding unitscorresponding to each depth included in the largest coding unit 610.

The number of deeper coding units according to depths including data inthe same range and the same size increases as the depth deepens. Forexample, four coding units corresponding to a depth of 2 are required tocover data that is included in one coding unit corresponding to a depthof 1. Accordingly, in order to compare encoding results of the same dataaccording to depths, the coding unit corresponding to the depth of 1 andfour coding units corresponding to the depth of 2 are each encoded.

In order to perform encoding for a current depth from among the depths,a least encoding error that is a representative encoding error may beselected for the current depth by performing encoding for eachprediction unit in the coding units corresponding to the current depth,along the horizontal axis of the hierarchical structure 600.Alternatively, the minimum encoding error may be searched for bycomparing representative encoding errors according to depths, byperforming encoding for each depth as the depth deepens along thevertical axis of the hierarchical structure 600. A depth and a partitionhaving the minimum encoding error in the coding unit 610 may be selectedas the final depth and a partition mode of the coding unit 610.

FIG. 14 illustrates a diagram for describing a relationship between acoding unit 710 and transformation units 720, according to variousembodiments.

The video encoding apparatus 100 according to the present embodiment orthe video decoding apparatus 200 according to the present embodimentencodes or decodes an image according to coding units having sizessmaller than or equal to a largest coding unit for each largest codingunit. Sizes of transformation units for transformation during encodingmay be selected based on data units that are not larger than acorresponding coding unit.

For example, in the video encoding apparatus 100 or the video decodingapparatus 200, if a size of the coding unit 710 is 64×64, transformationmay be performed by using the transformation units 720 having a size of32×32.

Also, data of the coding unit 710 having the size of 64×64 may beencoded by performing the transformation on each of the transformationunits having the size of 32×32, 16×16, 8×8, and 4×4, which are smallerthan 64×64, and then a transformation unit having the least coding errorwith respect to an original image may be selected.

FIG. 15 illustrates a plurality of pieces of encoding informationaccording to depths, according to various embodiments.

The output unit 130 of the video encoding apparatus 100 may encode andtransmit partition mode information 800, prediction mode information810, and transformation unit size information 820 for each coding unitcorresponding to a depth, as split information.

The partition mode information 800 indicates information about a shapeof a partition obtained by splitting a prediction unit of a currentcoding unit, wherein the partition is a data unit for predictionencoding the current coding unit. For example, a current coding unitCU_0 having a size of 2N×2N may be split into any one of a partition 802having a size of 2N×2N, a partition 804 having a size of 2N×N, apartition 806 having a size of N×2N, and a partition 808 having a sizeof N×N. Here, the partition mode information 800 is set to indicate oneof the partition 804 having a size of 2N×N, the partition 806 having asize of N×2N, and the partition 808 having a size of N×N.

The prediction mode information 810 indicates a prediction mode of eachpartition. For example, the prediction mode information 810 may indicatea mode of prediction encoding performed on a partition indicated by thepartition mode information 800, i.e., an intra mode 812, an inter mode814, or a skip mode 816.

The transformation unit size information 820 indicates a transformationunit to be based on when transformation is performed on a current codingunit. For example, the transformation unit may be a first intratransformation unit 822, a second intra transformation unit 824, a firstinter transformation unit 826, or a second inter transformation unit828.

The image data and encoding information extractor 220 of the videodecoding apparatus 200 may extract and use the partition modeinformation 800, the prediction mode information 810, and thetransformation unit size information 820 for decoding, according to eachdeeper coding unit.

FIG. 16 is a diagram of deeper coding units according to depths,according to various embodiments.

Split information may be used to indicate a change of a depth. The spiltinformation indicates whether a coding unit of a current depth is splitinto coding units of a lower depth.

A prediction unit 910 for prediction encoding a coding unit 900 having adepth of 0 and a size of 2N_0×2N_0 may include partitions of a partitionmode 912 having a size of 2N_0×2N_0, a partition mode 914 having a sizeof 2N_0×N_0, a partition mode 916 having a size of N_0×2N_0, and apartition mode 918 having a size of N_0×N_0. FIG. 23 only illustratesthe partition modes 912 through 918 which are obtained by symmetricallysplitting the prediction unit 910, but a partition mode is not limitedthereto, and the partitions of the prediction unit 910 may includeasymmetrical partitions, partitions having a predetermined shape, andpartitions having a geometrical shape.

Prediction encoding is repeatedly performed on one partition having asize of 2N_0×2N_0, two partitions having a size of 2N_0×N_0, twopartitions having a size of N_0×2N_0, and four partitions having a sizeof N_0×N_0, according to each partition mode.

The prediction encoding in an intra mode and an inter mode may beperformed on the partitions having the sizes of 2N_0×2N_0, N_0×2N_0,2N_0×N_0, and N_0×N_0. The prediction encoding in a skip mode isperformed only on the partition having the size of 2N_0×2N_0.

If an encoding error is smallest in one of the partition modes 912, 914,and 916 having the sizes of 2N_0×2N_0, 2N_0×N_0 and N_0×2N_0, theprediction unit 910 may not be split into a lower depth.

If the encoding error is the smallest in the partition mode 918 havingthe size of N_0×N_0, a depth is changed from 0 to 1 to split thepartition mode 918 in operation 920, and encoding is repeatedlyperformed on coding units 930 having a depth of 2 and a size of N_0×N_0to search for a minimum encoding error.

A prediction unit 940 for prediction encoding the coding unit 930 havinga depth of 1 and a size of 2N_1×2N_1 (=N_0×N_0) may include partitionsof a partition mode 942 having a size of 2N_1×2N_1, a partition mode 944having a size of 2N_1×N_1, a partition mode 946 having a size ofN_1×2N_1, and a partition mode 948 having a size of N_1×N_1.

If an encoding error is the smallest in the partition mode 948 havingthe size of N_1×N_1, a depth is changed from 1 to 2 to split thepartition mode 948 in operation 950, and encoding is repeatedlyperformed on coding units 960, which have a depth of 2 and a size ofN_2×N_2 to search for a minimum encoding error.

When a maximum depth is d, split operation according to each depth maybe performed up to when a depth becomes d−1, and split information maybe encoded as up to when a depth is one of 0 to d−2. In other words,when encoding is performed up to when the depth is d−1 after a codingunit corresponding to a depth of d−2 is split in operation 970, aprediction unit 990 for prediction encoding a coding unit 980 having adepth of d−1 and a size of 2N_(d−1)×2N_(d−1) may include partitions of apartition mode 992 having a size of 2N_(d−1)×2N_(d−1), a partition mode994 having a size of 2N_(d−1)×N_(d−1), a partition mode 996 having asize of N_(d−1)×2N_(d−1), and a partition mode 998 having a size ofN_(d−1)×N_(d−1).

Prediction encoding may be repeatedly performed on one partition havinga size of 2N_(d−1)×2N_(d−1), two partitions having a size of2N_(d−1)×N_(d−1), two partitions having a size of N_(d−1)×2N_(d−1), fourpartitions having a size of N_(d−1)×N_(d−1) from among the partitionmodes 992 through 998 to search for a partition mode having a minimumencoding error.

Even when the partition mode 998 having the size of N_(d−1)×N_(d−1) hasthe minimum encoding error, since a maximum depth is d, a coding unitCU_(d−1) having a depth of d−1 is no longer split into a lower depth,and a depth for the coding units constituting a current largest codingunit 900 is determined to be d−1 and a partition mode of the currentlargest coding unit 900 may be determined to be N_(d−1)×N_(d−1). Also,since the maximum depth is d, split information for the coding unit 952having a depth of d−1 is not set.

A data unit 999 may be a ‘minimum unit’ for the current largest codingunit. A minimum unit according to the embodiment may be a square dataunit obtained by splitting a minimum coding unit 980 having a lowermostdepth by 4. By performing the encoding repeatedly, the video encodingapparatus 100 according to the embodiment may select a depth having theleast encoding error by comparing encoding errors according to depths ofthe coding unit 900 to determine a depth, and set a correspondingpartition mode and a prediction mode as an encoding mode of the depth.

As such, the minimum encoding errors according to depths are compared inall of the depths of 0, 1, . . . , d−1, d, and a depth having the leastencoding error may be determined as a depth. The depth, the partitionmode of the prediction unit, and the prediction mode may be encoded andtransmitted as split information. Also, since a coding unit is splitfrom a depth of 0 to a depth, only split information of the depth is setto ‘0’, and split information of depths excluding the depth is set to‘1’.

The image data and encoding information extractor 220 of the videodecoding apparatus 200 according to the embodiment may extract and usethe information about the depth and the prediction unit of the codingunit 900 to decode the partition 912. The video decoding apparatus 200according to the embodiment may determine a depth, in which splitinformation is ‘0’, as a depth by using split information according todepths, and use split information of the corresponding depth fordecoding.

FIGS. 17, 18, and 19 are diagrams for describing a relationship betweencoding units, prediction units, and transformation units, according tovarious embodiments.

Coding units 1010 are deeper coding units according to depths determinedby the video encoding apparatus 100, in a largest coding unit.Prediction units 1060 are partitions of prediction units of each of thecoding units 1010, and transformation units 1070 are transformationunits of each of the coding units 1010.

When a depth of a largest coding unit is 0 in the coding units 1010,depths of coding units 1012 and 1054 are 1, depths of coding units 1014,1016, 1018, 1028, 1050, and 1052 are 2, depths of coding units 1020,1022, 1024, 1026, 1030, 1032, and 1048 are 3, and depths of coding units1040, 1042, 1044, and 1046 are 4.

In the prediction units 1060, some encoders 1014, 1016, 1022, 1032,1048, 1050, 1052, and 1054 are obtained by splitting the coding units inthe encoders 1010. That is, partition modes in the coding units 1014,1022, 1050, and 1054 have a size of 2N×N, partition modes in the codingunits 1016, 1048, and 1052 have a size of N×2N, and a partition mode ofthe coding unit 1032 has a size of N×N. Prediction units and partitionsof the coding units 1010 are smaller than or equal to each coding unit.

Transformation or inverse transformation is performed on image data ofthe coding unit 1052 in the transformation units 1070 in a data unitthat is smaller than the coding unit 1052. Also, the coding units 1014,1016, 1022, 1032, 1048, 1050, and 1052 in the transformation units 1070are different from those in the prediction units 1060 in terms of sizesand shapes. That is, the video encoding apparatus 100 according to thepresent embodiment and the video decoding apparatus 200 according to thepresent embodiment may perform intra prediction/motion estimation/motioncompensation/and transformation/inverse transformation individually on adata unit in the same coding unit.

Accordingly, encoding is recursively performed on each of coding unitshaving a hierarchical structure in each region of a largest coding unitto determine an optimum coding unit, and thus coding units having arecursive tree structure may be obtained. Encoding information mayinclude split information about a coding unit, information about apartition mode, information about a prediction mode, and informationabout a size of a transformation unit. Table 1 below shows the encodinginformation that may be set by the video encoding apparatus 100 and thevideo decoding apparatus 200 according to the embodiments.

TABLE 1 Split Information 0 (Encoding on Coding Unit having Size of 2N ×2N and Current Depth of d) Size of Transformation Unit PredictionPartition mode Split Split Mode Symmetrical Information 0 of Information1 of Intra Partition Asymmetrical Transformation Transformation SplitInter mode Partition mode Unit Unit Information 1 Skip (Only 2N × 2N 2N× nU 2N × 2N N × N Repeatedly 2N × 2N) 2N × N 2N × nD (SymmetricalEncode Coding N × 2N nL × 2N Partition mode) Units having N × N nR × 2NN/2 × N/2 Lower Depth (Asymmetrical of d + 1 Partition mode)

The output unit 130 of the video encoding apparatus 100 according to thepresent embodiment may output the encoding information about the codingunits having a tree structure, and the image data and encodinginformation extractor 220 of the video decoding apparatus 200 accordingto the embodiment may extract the encoding information about the codingunits having a tree structure from a received bitstream.

Split information indicates whether a current coding unit is split intocoding units of a lower depth. If split information of a current depth dis 0, a depth, in which a current coding unit is no longer split into alower depth, is a depth, and thus information about a partition mode,prediction mode, and a size of a transformation unit may be defined forthe depth. If the current coding unit is further split according to thesplit information, encoding is independently performed on four splitcoding units of a lower depth.

A prediction mode may be one of an intra mode, an inter mode, and a skipmode. The intra mode and the inter mode may be defined in all partitionmodes, and the skip mode is defined only in a partition mode having asize of 2N×2N.

The information about the partition mode may indicate symmetricalpartition modes having sizes of 2N×2N, 2N×N, N×2N, and N×N, which areobtained by symmetrically splitting a height or a width of a predictionunit, and asymmetrical partition modes having sizes of 2N×nU, 2N×nD,nL×2N, and nR×2N, which are obtained by asymmetrically splitting theheight or width of the prediction unit. The asymmetrical partition modeshaving the sizes of 2N×nU and 2N×nD may be respectively obtained bysplitting the height of the prediction unit in 1:3 and 3:1, and theasymmetrical partition modes having the sizes of nL×2N and nR×2N may berespectively obtained by splitting the width of the prediction unit in1:3 and 3:1.

The size of the transformation unit may be set to be two types in theintra mode and two types in the inter mode. In other words, if splitinformation of the transformation unit is 0, the size of thetransformation unit may be 2N×2N, which is the size of the currentcoding unit. If split information of the transformation unit is 1, thetransformation units may be obtained by splitting the current codingunit. Also, if a partition mode of the current coding unit having thesize of 2N×2N is a symmetrical partition mode, a size of atransformation unit may be N×N, and if the partition mode of the currentcoding unit is an asymmetrical partition mode, the size of thetransformation unit may be N/2×N/2.

The encoding information about coding units having a tree structureaccording to the embodiment may be assigned to at least one selectedfrom a coding unit corresponding to a depth, a prediction unit, and aminimum unit. The coding unit corresponding to the depth may include atleast one selected from a prediction unit and a minimum unit containingthe same encoding information.

Accordingly, it is determined whether adjacent data units are includedin the same coding unit corresponding to the final depth by comparingencoding information of the adjacent data units. Also, a correspondingcoding unit corresponding to a final depth is determined by usingencoding information of a data unit, and thus a distribution of finaldepths in a largest coding unit may be determined.

Accordingly, if a current coding unit is predicted based on encodinginformation of adjacent data units, encoding information of data unitsin deeper coding units adjacent to the current coding unit may bedirectly referred to and used.

In another embodiment, if a current coding unit is predicted based onencoding information of adjacent data units, data units adjacent to thecurrent coding unit are searched using encoded information of the dataunits, and the searched adjacent coding units may be referred forpredicting the current coding unit.

FIG. 20 illustrates a diagram for describing a relationship between acoding unit, a prediction unit, and a transformation unit, according toencoding mode information of Table 1.

A largest coding unit 1300 includes coding units 1302, 1304, 1306, 1312,1314, 1316, and 1318 of depths. Here, since the coding unit 1318 is acoding unit of a depth, split information may be set to 0. Informationabout a partition mode of the coding unit 1318 having a size of 2N×2Nmay be set to be one of partition modes including 2N×2N 1322, 2N×N 1324,N×2N 1326, N×N 1328, 2N×nU 1332, 2N×nD 1334, nL×2N 1336, and nR×2N 1338.

Transformation unit split information (TU size flag) is a type of atransformation index. A size of a transformation unit corresponding tothe transformation index may be changed according to a prediction unittype or partition mode of the coding unit.

For example, when the information about the partition mode is set to beone of symmetrical partition modes 2N×2N 1322, 2N×N 1324, N×2N 1326, andN×N 1328, if the transformation unit split information is 0, atransformation unit 1342 having a size of 2N×2N is set, and if thetransformation unit split information is 1, a transformation unit 1344having a size of N×N is set.

When the information about the partition mode is set to be one ofasymmetrical partition modes 2N×nU 1332, 2N×nD 1334, nL×2N 1336, andnR×2N 1338, if the transformation unit split information is 0, atransformation unit 1352 having a size of 2N×2N may be set, and if thetransformation unit split information is 1, a transformation unit 1354having a size of N/2×N/2 may be set.

As described above with reference to FIG. 19, the transformation unitsplit information (TU size flag) is a flag having a value or 0 or 1, butthe transformation unit split information is not limited to a flaghaving 1 bit, and the transformation unit may be hierarchically splitwhile the transformation unit split information increases in a manner of0, 1, 2, 3 . . . etc., according to setting. The transformation unitsplit information may be an example of the transformation index.

In this case, the size of a transformation unit that has been actuallyused may be expressed by using the transformation unit split informationaccording to the embodiment, together with a maximum size of thetransformation unit and a minimum size of the transformation unit. Thevideo encoding apparatus 100 according to the embodiment is capable ofencoding maximum transformation unit size information, minimumtransformation unit size information, and maximum transformation unitsplit information. The result of encoding the maximum transformationunit size information, the minimum transformation unit size information,and the maximum transformation unit split information may be insertedinto an SPS. The video decoding apparatus 200 according to theembodiment may decode video by using the maximum transformation unitsize information, the minimum transformation unit size information, andthe maximum transformation unit split information.

For example, (a) if the size of a current coding unit is 64×64 and amaximum transformation unit size is 32×32, (a−1) then the size of atransformation unit may be 32×32 when a TU size flag is 0, (a−2) may be16×16 when the TU size flag is 1, and (a−3) may be 8×8 when the TU sizeflag is 2.

As another example, (b) if the size of the current coding unit is 32×32and a minimum transformation unit size is 32×32, (b−1) then the size ofthe transformation unit may be 32×32 when the TU size flag is 0. Here,the TU size flag cannot be set to a value other than 0, since the sizeof the transformation unit cannot be less than 32×32.

As another example, (c) if the size of the current coding unit is 64×64and a maximum TU size flag is 1, then the TU size flag may be 0 or 1.Here, the TU size flag cannot be set to a value other than 0 or 1.

Thus, if it is defined that the maximum TU size flag is‘MaxTransformSizeIndex’, a minimum transformation unit size is‘MinTransformSize’, and a transformation unit size is ‘RootTuSize’ whenthe TU size flag is 0, then a current minimum transformation unit size‘CurrMinTuSize’ that can be determined in a current coding unit may bedefined by Equation (1):

CurrMinTuSize=max(MinTransformSize,RootTuSize/(2̂MaxTransformSizeIndex))  (1)

Compared to the current minimum transformation unit size ‘CurrMinTuSize’that can be determined in the current coding unit, a transformation unitsize ‘RootTuSize’ when the TU size flag is 0 may denote a maximumtransformation unit size that can be selected in the system. That is, inEquation (1), ‘RootTuSize/(2̂MaxTransformSizeIndex)’ denotes atransformation unit size when the transformation unit size ‘RootTuSize’,when the TU size flag is 0, is split by the number of timescorresponding to the maximum TU size flag, and ‘MinTransformSize’denotes a minimum transformation size. Thus, a smaller value from among‘RootTuSize/(2̂MaxTransformSizeIndex)’ and ‘MinTransformSize’ may be thecurrent minimum transformation unit size ‘CurrMinTuSize’ that can bedetermined in the current coding unit.

According to an embodiment, the maximum transformation unit sizeRootTuSize may vary according to the type of a prediction mode.

For example, if a current prediction mode is an inter mode, then‘RootTuSize’ may be determined by using Equation (2) below. In Equation(2), ‘MaxTransformSize’ denotes a maximum transformation unit size, and‘PUSize’ denotes a current prediction unit size.

RootTuSize=min(MaxTransformSize,PUSize)  (2)

That is, if the current prediction mode is the inter mode, thetransformation unit size ‘RootTuSize’, when the TU size flag is 0, maybe a smaller value from among the maximum transformation unit size andthe current prediction unit size.

If a prediction mode of a current partition unit is an intra mode,‘RootTuSize’ may be determined by using Equation (3) below. In Equation(3), ‘PartitionSize’ denotes the size of the current partition unit.

RootTuSize=min(MaxTransformSize,PartitionSize)  (3)

That is, if the current prediction mode is the intra mode, thetransformation unit size ‘RootTuSize’ when the TU size flag is 0 may bea smaller value from among the maximum transformation unit size and thesize of the current partition unit.

However, the current maximum transformation unit size ‘RootTuSize’ thatvaries according to the type of a prediction mode in a partition unit isjust an embodiment, and a factor for determining the current maximumtransformation unit size is not limited thereto.

According to the video encoding method based on coding units of a treestructure described above with reference to FIGS. 8 through 20, imagedata of a spatial domain is encoded in each of the coding units of thetree structure, and the image data of the spatial domain isreconstructed in a manner that decoding is performed on each largestcoding unit according to the video decoding method based on the codingunits of the tree structure, so that a video that is formed of picturesand pictures sequences may be reconstructed. The reconstructed video maybe reproduced by a reproducing apparatus, may be stored in a storagemedium, or may be transmitted via a network.

The one or more embodiments can be written as computer programs and canbe implemented in general-use digital computers that execute theprograms using a computer readable recording medium. Examples of thecomputer readable recording medium include magnetic storage media (e.g.,ROM, floppy disks, hard disks, etc.), optical recording media (e.g.,CD-ROMs, or DVDs), etc.

For convenience of description, the aforementioned video encodingmethods and/or video encoding methods are collectively referred to as‘the video encoding method of the present invention’. Also, theaforementioned video decoding methods and/or video decoding methods arereferred to as ‘the video decoding method of the present invention’.

Also, a video encoding apparatus including the video encoding apparatus40, the video encoding apparatus 100, or the image encoder 400 iscollectively referred as a ‘video encoding apparatus of the presentinvention’. Also, a video decoding apparatus including the device 10,the video decoding apparatus 200, or the image decoder 500 iscollectively referred to as a ‘video decoding apparatus of the presentinvention’.

A computer-readable recording medium storing a program, e.g., a disc26000, according to an embodiment will now be described in detail.

FIG. 21 illustrates a diagram of a physical structure of the disc 26000in which a program is stored, according to various embodiments. The disc26000, which is a storage medium, may be a hard drive, a compactdisc-read only memory (CD-ROM) disc, a Blu-ray disc, or a digitalversatile disc (DVD). The disc 26000 includes a plurality of concentrictracks Tr that are each divided into a specific number of sectors Se ina circumferential direction of the disc 26000. In a specific region ofthe disc 26000, a program that executes the quantized parameterdetermining method, the video encoding method, and the video decodingmethod described above may be assigned and stored.

A computer system embodied using a storage medium that stores a programfor executing the video encoding method and the video decoding method asdescribed above will now be described with reference to FIG. 22.

FIG. 22 illustrates a diagram of a disc drive 26800 for recording andreading a program by using the disc 26000. A computer system 26700 maystore a program that executes at least one selected from a videoencoding method and a video decoding method according to an embodiment,in the disc 26000 via the disc drive 26800. To run the program stored inthe disc 26000 in the computer system 26700, the program may be readfrom the disc 26000 and be transmitted to the computer system 26700 byusing the disc drive 26800.

The program that executes at least one selected from a video encodingmethod and a video decoding method according to an embodiment may bestored not only in the disc 26000 illustrated in FIGS. 21 and 22 butalso may be stored in a memory card, a ROM cassette, or a solid statedrive (SSD).

A system to which the video encoding method and the video decodingmethod described above are applied will be described below.

FIG. 23 illustrates a diagram of an overall structure of a contentsupply system 11000 for providing a content distribution service. Aservice area of a communication system is divided intopredetermined-sized cells, and wireless base stations 11700, 11800,11900, and 12000 are installed in these cells, respectively.

The content supply system 11000 includes a plurality of independentdevices. For example, the plurality of independent devices, such as acomputer 12100, a personal digital assistant (PDA) 12200, a video camera12300, and a mobile phone 12500, are connected to the Internet 11100 viaan internet service provider 11200, a communication network 11400, andthe wireless base stations 11700, 11800, 11900, and 12000.

However, the content supply system 11000 is not limited to asillustrated in FIG. 23, and devices may be selectively connectedthereto. The plurality of independent devices may be directly connectedto the communication network 11400, not via the wireless base stations11700, 11800, 11900, and 12000.

The video camera 12300 is an imaging device, e.g., a digital videocamera, which is capable of capturing video images. The mobile phone12500 may employ at least one communication method from among variousprotocols, e.g., Personal Digital Communications (PDC), Code DivisionMultiple Access (CDMA), Wideband-Code Division Multiple Access (W-CDMA),Global System for Mobile Communications (GSM), and Personal HandyphoneSystem (PHS).

The video camera 12300 may be connected to a streaming server 11300 viathe wireless base station 11900 and the communication network 11400. Thestreaming server 11300 allows content received from a user via the videocamera 12300 to be streamed via a real-time broadcast. The contentreceived from the video camera 12300 may be encoded using the videocamera 12300 or the streaming server 11300. Video data captured by thevideo camera 12300 may be transmitted to the streaming server 11300 viathe computer 12100.

Video data captured by a camera 12600 may also be transmitted to thestreaming server 11300 via the computer 12100. The camera 12600 is animaging device capable of capturing both still images and video images,similar to a digital camera. The video data captured by the camera 12600may be encoded using the camera 12600 or the computer 12100. Softwarethat performs encoding and decoding video may be stored in acomputer-readable recording medium, e.g., a CD-ROM disc, a floppy disc,a hard disc drive, an SSD, or a memory card, which may be accessible bythe computer 12100.

If video data is captured by a camera built in the mobile phone 12500,the video data may be received from the mobile phone 12500.

The video data may also be encoded by a large scale integrated circuit(LSI) system installed in the video camera 12300, the mobile phone12500, or the camera 12600.

The content supply system 11000 may encode content data recorded by auser using the video camera 12300, the camera 12600, the mobile phone12500, or another imaging device, e.g., content recorded during aconcert, and transmit the encoded content data to the streaming server11300. The streaming server 11300 may transmit the encoded content datain a type of a streaming content to other clients that request thecontent data.

The clients are devices capable of decoding the encoded content data,e.g., the computer 12100, the PDA 12200, the video camera 12300, or themobile phone 12500. Thus, the content supply system 11000 allows theclients to receive and reproduce the encoded content data. Also, thecontent supply system 11000 allows the clients to receive the encodedcontent data and decode and reproduce the encoded content data in realtime, thereby enabling personal broadcasting.

Encoding and decoding operations of the plurality of independent devicesincluded in the content supply system 11000 may be similar to those of avideo encoding apparatus and a video decoding apparatus according toembodiments.

With reference to FIGS. 24 and 25, the mobile phone 12500 included inthe content supply system 11000 according to an embodiment will now bedescribed in detail.

FIG. 24 illustrates an external structure of the mobile phone 12500 towhich a video encoding method and a video decoding method are applied,according to various embodiments. The mobile phone 12500 may be a smartphone, the functions of which are not limited and a large number of thefunctions of which may be changed or expanded.

The mobile phone 12500 includes an internal antenna 12510 via which aradio-frequency (RF) signal may be exchanged with the wireless basestation 12000, and includes a display screen 12520 for displaying imagescaptured by a camera 12530 or images that are received via the antenna12510 and decoded, e.g., a liquid crystal display (LCD) or an organiclight-emitting diode (OLED) screen. The mobile phone 12500 includes anoperation panel 12540 including a control button and a touch panel. Ifthe display screen 12520 is a touch screen, the operation panel 12540further includes a touch sensing panel of the display screen 12520. Themobile phone 12500 includes a speaker 12580 for outputting voice andsound or another type of a sound output unit, and a microphone 12550 forinputting voice and sound or another type of a sound input unit. Themobile phone 12500 further includes the camera 12530, such as acharge-coupled device (CCD) camera, to capture video and still images.The mobile phone 12500 may further include a storage medium 12570 forstoring encoded/decoded data, e.g., video or still images captured bythe camera 12530, received via email, or obtained according to variousways; and a slot 12560 via which the storage medium 12570 is loaded intothe mobile phone 12500. The storage medium 12570 may be a flash memory,e.g., a secure digital (SD) card or an electrically erasable andprogrammable read only memory (EEPROM) included in a plastic case.

FIG. 25 illustrates an internal structure of the mobile phone 12500. Inorder to systemically control parts of the mobile phone 12500 includingthe display screen 12520 and the operation panel 12540, a power supplycircuit 12700, an operation input controller 12640, an image encoder12720, a camera interface 12630, an LCD controller 12620, an imagedecoder 12690, a multiplexer/demultiplexer 12680, a recording/readingunit 12670, a modulation/demodulation unit 12660, and a sound processor12650 are connected to a central controller 12710 via a synchronizationbus 12730.

If a user operates a power button and sets from a ‘power off’ state to a‘power on’ state, the power supply circuit 12700 supplies power to allthe parts of the mobile phone 12500 from a battery pack, thereby settingthe mobile phone 12500 to an operation mode.

The central controller 12710 includes a central processing unit (CPU), aROM, and a RAM.

While the mobile phone 12500 transmits communication data to theoutside, a digital signal is generated by the mobile phone 12500 undercontrol of the central controller 12710. For example, the soundprocessor 12650 may generate a digital sound signal, the image encoder12720 may generate a digital image signal, and text data of a messagemay be generated via the operation panel 12540 and the operation inputcontroller 12640. When a digital signal is transmitted to themodulation/demodulation unit 12660 by control of the central controller12710, the modulation/demodulation unit 12660 modulates a frequency bandof the digital signal, and a communication circuit 12610 performsdigital-to-analog conversion (DAC) and frequency conversion on thefrequency band-modulated digital sound signal. A transmission signaloutput from the communication circuit 12610 may be transmitted to avoice communication base station or the wireless base station 12000 viathe antenna 12510.

For example, when the mobile phone 12500 is in a conversation mode, asound signal obtained via the microphone 12550 is transformed into adigital sound signal by the sound processor 12650, by control of thecentral controller 12710. The digital sound signal may be transformedinto a transformation signal via the modulation/demodulation unit 12660and the communication circuit 12610, and may be transmitted via theantenna 12510.

When a text message, e.g., email, is transmitted during a datacommunication mode, text data of the text message is input via theoperation panel 12540 and is transmitted to the central controller 12610via the operation input controller 12640. By control of the centralcontroller 12610, the text data is transformed into a transmissionsignal via the modulation/demodulation unit 12660 and the communicationcircuit 12610 and is transmitted to the wireless base station 12000 viathe antenna 12510.

In order to transmit image data during the data communication mode,image data captured by the camera 12530 is provided to the image encoder12720 via the camera interface 12630. The captured image data may bedirectly displayed on the display screen 12520 via the camera interface12630 and the LCD controller 12620.

A structure of the image encoder 12720 may correspond to that of thevideo encoding apparatus 100 described above. The image encoder 12720may transform the image data received from the camera 12530 intocompressed and encoded image data according to the aforementioned videoencoding method, and then output the encoded image data to themultiplexer/demultiplexer 12680. During a recording operation of thecamera 12530, a sound signal obtained by the microphone 12550 of themobile phone 12500 may be transformed into digital sound data via thesound processor 12650, and the digital sound data may be transmitted tothe multiplexer/demultiplexer 12680.

The multiplexer/demultiplexer 12680 multiplexes the encoded image datareceived from the image encoder 12720, together with the sound datareceived from the sound processor 12650. A result of multiplexing thedata may be transformed into a transmission signal via themodulation/demodulation unit 12660 and the communication circuit 12610,and may then be transmitted via the antenna 12510.

While the mobile phone 12500 receives communication data from theoutside, frequency recovery and ADC are performed on a signal receivedvia the antenna 12510 to transform the signal into a digital signal. Themodulation/demodulation unit 12660 modulates a frequency band of thedigital signal. The frequency-band modulated digital signal istransmitted to the video decoder 12690, the sound processor 12650, orthe LCD controller 12620, according to the type of the digital signal.

During the conversation mode, the mobile phone 12500 amplifies a signalreceived via the antenna 12510, and obtains a digital sound signal byperforming frequency conversion and ADC on the amplified signal. Areceived digital sound signal is transformed into an analog sound signalvia the modulation/demodulation unit 12660 and the sound processor12650, and the analog sound signal is output via the speaker 12580, bycontrol of the central controller 12710.

When during the data communication mode, data of a video file accessedat an Internet website is received, a signal received from the wirelessbase station 12000 via the antenna 12510 is output as multiplexed datavia the modulation/demodulation unit 12660, and the multiplexed data istransmitted to the multiplexer/demultiplexer 12680.

In order to decode the multiplexed data received via the antenna 12510,the multiplexer/demultiplexer 12680 demultiplexes the multiplexed datainto an encoded video data stream and an encoded audio data stream. Viathe synchronization bus 12730, the encoded video data stream and theencoded audio data stream are provided to the video decoder 12690 andthe sound processor 12650, respectively.

A structure of the image decoder 12690 may correspond to that of thevideo decoding apparatus described above. The image decoder 12690 maydecode the encoded video data to obtain reconstructed video data andprovide the reconstructed video data to the display screen 12520 via theLCD controller 12620, by using the aforementioned video decoding methodaccording to the embodiment.

Thus, the data of the video file accessed at the Internet website may bedisplayed on the display screen 12520. At the same time, the soundprocessor 12650 may transform audio data into an analog sound signal,and provide the analog sound signal to the speaker 12580. Thus, audiodata contained in the video file accessed at the Internet website mayalso be reproduced via the speaker 12580.

The mobile phone 12500 or another type of communication terminal may bea transceiving terminal including both a video encoding apparatus and avideo decoding apparatus according to an embodiment, may be atransmitting terminal including only the video encoding apparatus, ormay be a receiving terminal including only the video decoding apparatus.

A communication system according to an embodiment is not limited to thecommunication system described above with reference to FIG. 24. Forexample, FIG. 26 illustrates a digital broadcasting system employing acommunication system, according to various embodiments. The digitalbroadcasting system of FIG. 26 may receive a digital broadcasttransmitted via a satellite or a terrestrial network by using the videoencoding apparatus and the video decoding apparatus according to theembodiments.

In more detail, a broadcasting station 12890 transmits a video datastream to a communication satellite or a broadcasting satellite 12900 byusing radio waves. The broadcasting satellite 12900 transmits abroadcast signal, and the broadcast signal is transmitted to a satellitebroadcast receiver via a household antenna 12860. In every house, anencoded videostream may be decoded and reproduced by a TV receiver12810, a set-top box 12870, or another device.

When the video decoding apparatus according to the embodiment isimplemented in a reproducing apparatus 12830, the reproducing apparatus12830 may parse and decode an encoded videostream recorded on a storagemedium 12820, such as a disc or a memory card to reconstruct digitalsignals. Thus, the reconstructed video signal may be reproduced, forexample, on a monitor 12840.

In the set-top box 12870 connected to the antenna 12860 for asatellite/terrestrial broadcast or a cable antenna 12850 for receiving acable television (TV) broadcast, the video decoding apparatus accordingto the embodiment may be installed. Data output from the set-top box12870 may also be reproduced on a TV monitor 12880.

As another example, the video decoding apparatus according to theembodiment may be installed in the TV receiver 12810 instead of theset-top box 12870.

An automobile 12920 that has an appropriate antenna 12910 may receive asignal transmitted from the satellite 12900 or the wireless base station11700. A decoded video may be reproduced on a display screen of anautomobile navigation system 12930 installed in the automobile 12920.

A video signal may be encoded by the video encoding apparatus accordingto the embodiment and may then be stored in a storage medium. In moredetail, an image signal may be stored in a DVD disc 12960 by a DVDrecorder or may be stored in a hard disc by a hard disc recorder 12950.As another example, the video signal may be stored in an SD card 12970.If the hard disc recorder 12950 includes the video decoding apparatusaccording to the embodiment, a video signal recorded on the DVD disc12960, the SD card 12970, or another storage medium may be reproduced onthe TV monitor 12880.

The automobile navigation system 12930 may not include the camera 12530,the camera interface 12630, and the image encoder 12720 of FIG. 25. Forexample, the computer 12100 and the TV receiver 12810 may not includethe camera 12530, the camera interface 12630, and the image encoder12720 of FIG. 25.

FIG. 27 is a diagram illustrating a network structure of a cloudcomputing system using a video encoding apparatus and a video decodingapparatus, according to various embodiments.

The cloud computing system may include a cloud computing server 14000, auser database (DB) 14100, a plurality of computing resources 14200, anda user terminal.

The cloud computing system provides an on-demand outsourcing service ofthe plurality of computing resources 14200 via a data communicationnetwork, e.g., the Internet, in response to a request from the userterminal. Under a cloud computing environment, a service providerprovides users with desired services by combining computing resources atdata centers located at physically different locations by usingvirtualization technology. A service user does not have to installcomputing resources, e.g., an application, a storage, an operatingsystem (OS), and security software, into his/her own terminal in orderto use them, but may select and use desired services from among servicesin a virtual space generated through the virtualization technology, at adesired point in time.

A user terminal of a specified service user is connected to the cloudcomputing server 14000 via a data communication network including theInternet and a mobile telecommunication network. User terminals may beprovided cloud computing services, and particularly video reproductionservices, from the cloud computing server 14000. The user terminals maybe various types of electronic devices capable of being connected to theInternet, e.g., a desktop PC 14300, a smart TV 14400, a smart phone14500, a notebook computer 14600, a portable multimedia player (PMP)14700, a tablet PC 14800, and the like.

The cloud computing server 14000 may combine the plurality of computingresources 14200 distributed in a cloud network and provide userterminals with a result of combining. The plurality of computingresources 14200 may include various data services, and may include datauploaded from user terminals. As described above, the cloud computingserver 14000 may provide user terminals with desired services bycombining video database distributed in different regions according tothe virtualization technology.

User information about users who have subscribed for a cloud computingservice is stored in the user DB 14100. The user information may includelogging information, addresses, names, and personal credit informationof the users. The user information may further include indexes ofvideos. Here, the indexes may include a list of videos that have alreadybeen reproduced, a list of videos that are being reproduced, a pausingpoint of a video that was being reproduced, and the like.

Information about a video stored in the user DB 14100 may be sharedbetween user devices. For example, when a video service is provided tothe notebook computer 14600 in response to a request from the notebookcomputer 14600, a reproduction history of the video service is stored inthe user DB 14100. When a request to reproduce the video service isreceived from the smart phone 14500, the cloud computing server 14000searches for and reproduces the video service, based on the user DB14100. When the smart phone 14500 receives a video data stream from thecloud computing server 14000, a process of reproducing video by decodingthe video data stream is similar to an operation of the mobile phone12500 described above with reference to FIG. 24.

The cloud computing server 14000 may refer to a reproduction history ofa desired video service, stored in the user DB 14100. For example, thecloud computing server 14000 receives a request to reproduce a videostored in the user DB 14100, from a user terminal. If this video wasbeing reproduced, then a method of streaming this video, performed bythe cloud computing server 14000, may vary according to the request fromthe user terminal, i.e., according to whether the video will bereproduced, starting from a start thereof or a pausing point thereof.For example, if the user terminal requests to reproduce the video,starting from the start thereof, the cloud computing server 14000transmits streaming data of the video starting from a first framethereof to the user terminal. If the user terminal requests to reproducethe video, starting from the pausing point thereof, the cloud computingserver 14000 transmits streaming data of the video starting from a framecorresponding to the pausing point, to the user terminal.

In this case, the user terminal may include the aforementioned videodecoding apparatus of the present invention. In another example, theuser terminal may include the video encoding apparatus of the presentinvention. Alternatively, the user terminal may include both the videodecoding apparatus and the video encoding apparatus of the presentinvention.

Various applications of the video encoding method, the video decodingmethod, the video encoding apparatus, and the video decoding apparatusare described above with reference to FIGS. 21 through 27. However,methods of storing the video encoding method and the video decodingmethod in a storage medium or methods of implementing the video encodingapparatus and the video decoding apparatus in a device are not limitedto the embodiments described above with reference to FIGS. 21 through27.

As described above, when the methods of improving performance of digitalsignal transformation, and the transform matrices according to variousembodiments are used in digital signal transformation and digital signalprocessing, the transform matrices are determined based on exactlimitation conditions. Compared to the related art, the digital signaltransformation according to various embodiments has higher decorrelationcapability and lower transform distortion.

The aforementioned various embodiments are not provided to limit thescope of the present invention. Thus, the invention may include allrevisions, equivalents, or substitutions which are included in theconcept and the technical scope related to the invention.

The aforementioned terms such as “include”, “comprise”, “configure”,“have”, or the like are used to mean that, unless there is a particulardescription contrary thereto, a corresponding element may be includedtherein, and other elements are not excluded and may also be furtherincluded therein.

The embodiments of the present invention can be written as computerprograms and can be implemented in general-use digital computers thatexecute the programs using a computer readable recording medium.Examples of the computer readable recording medium include magneticstorage media (e.g., ROM, floppy disks, hard disks, etc.), opticalrecording media (e.g., CD-ROMs, or DVDs), etc.

While this present invention has been particularly shown and describedwith reference to embodiments thereof, it will be understood by those ofordinary skill in the art that various changes in form and details maybe made therein without departing from the spirit and scope of thefollowing claims. The embodiments should be considered in a descriptivesense only and not for purposes of limitation. Therefore, the scope ofthe present invention is defined not by the detailed description of thepresent invention but by the appended claims, and all differences withinthe scope will be construed as being included in the present invention.

What is claimed is:
 1. An inverse-transforming method comprising:determining a transform block including transform coefficients;obtaining first transformed coefficients by applying a first transformmatrix to the transform block and by performing right-shifting by afirst number of bits; obtaining second transformed coefficients byapplying a second transform matrix to the first transformed coefficientsand by performing right-shifting by a second number of bits; obtaining aresidual block based on the second transformed coefficients; andobtaining a residual block based on the second transformed coefficients,wherein the first number of bits and the second number of bits areseparately predetermined.
 2. The inverse-transforming method of claim 1,wherein the first transform matrix is a matrix configured of {{32, 32,32, 32}, {42, 17, −17, −42}, {32, −32, −32, 32}, {17, −42, 42, −17}}. 3.The inverse-transforming method of claim 1, wherein the first number ofbits is different from the second number of bits.
 4. Aninverse-transforming apparatus comprising: a block determiner configuredto determine a transform block including transform coefficients; aprocessor configured to obtain first transformed coefficients byapplying a first transform matrix to the transform block and byperforming right-shifting by a first number of bits, obtain secondtransformed coefficients by applying a second transform matrix to thefirst transformed coefficients and by performing right-shifting by asecond number of bits, and obtain a residual block based on the secondtransformed coefficients, wherein the first number of bits and thesecond number of bits are separately predetermined.
 5. Theinverse-transforming apparatus of claim 4, wherein the first transformmatrix is a matrix configured of {{32, 32, 32, 32}, {42, 17, −17, −42},{32, −32, −32, 32}, {17, −42, 42, −17}}.
 6. The inverse-transformingapparatus of claim 4, wherein the first number of bits is different fromthe second number of bits.
 7. A transforming method comprising:determining a transform unit corresponding to a residual block;obtaining first transformed coefficients by applying a first transformmatrix to the transform unit and by performing right-shifting by a firstnumber of bits; obtaining second transformed coefficients by applying asecond transform matrix to the first transformed coefficients and byperforming right-shifting by a second number of bits; and obtaining atransform block including transform coefficients based on the secondtransformed coefficients, wherein the first number of bits and thesecond number of bits are separately predetermined.
 8. The transformingmethod of claim 7, wherein the first transform matrix is one of a matrixconfigured of {{32, 32, 32, 32}, {42, 17, −17, −42}, {32, −32, −32, 32},{17, −42, 42, −17}} and a transposed matrix of the matrix.
 9. Thetransforming method of claim 7, wherein the first number of bits isdifferent from the second number of bits.
 10. A transforming apparatuscomprising: a block determiner configured to determine a transform unitcorresponding to a residual block; and a transformer configured toobtain first transformed coefficients by applying a first transformmatrix to the transform unit and by performing right-shifting by a firstnumber of bits, obtain second transformed coefficients by applying asecond transform matrix to the first transformed coefficients and byperforming right-shifting by a second number of bits, and obtain atransform block including transform coefficients based on the secondtransformed coefficients, wherein the first number of bits and thesecond number of bits are separately predetermined.
 11. The transformingapparatus of claim 10, wherein the first transform matrix is one of amatrix configured of {{32, 32, 32, 32}, {42, 17, −17, −42}, {32, −32,−32, 32}, {17, −42, 42, −17}} and a transposed matrix of the matrix. 12.The transforming apparatus of claim 10, wherein the first number of bitsis different from the second number of bits.